American Express Membership Rewards - Amex or Visa for car rental CDW?

From the standpoint of the auto rental CDW program, is one coverage preferable between the Hilton Hhonors Amex or the Choice Privileges Visa from Bank of America? At this time I'd rather build up points on the Visa, but I'd like to know if Amex's coverage is better.

I don't know how my Visa (United Mileage Plus Platinum) or Amex cards (SPG, Rewards Gold Plus) compare to yours, but I'm looking at the same issue. I'll probably use the Visa for upcoming rentals in the UK because it is primary coverage overseas and clearly covers loss of use as well as damage. Well, OK -- another reason is that I'm getting double miles on car rentals through the Visa.

If you're using an Amex, another option is to sign up for the premium coverage. I forget the cost -- maybe $25 per rental? I considered doing that but will probably stick with the Visa.

Based on personal experience, AmEx will not cover you if you have any sort of 'free day' coupon. I rented a while back while overseas and used a free day coupon. Since I 'did not pay for the entire rental using AmEx' they refused to cover the damage claim. Of course I paid for as much of the rental that was out-of-pocket but they claimed using a free day coupon invalidated the collision damage waiver. Not sure if that is also true if one were to use $ off coupons, which are more common.

In the end my claim was reversed by a different division of AmEx as frivolous ($450 for a 1/2" scratch on the wheelwell that was probably there when I initiated the rental) but that is besides the point.

I now use Diners Club for my rentals - primary coverage anywhere in the world and costs under $100/year. Also gains me access to some airline clubs overseas.

Just know what is and is not covered before you venture out renting cars making basic assumptions that could be wrong.

I don't know how my Visa (United Mileage Plus Platinum) or Amex cards (SPG, Rewards Gold Plus) compare to yours, but I'm looking at the same issue. I'll probably use the Visa for upcoming rentals in the UK because it is primary coverage overseas and clearly covers loss of use as well as damage. Well, OK -- another reason is that I'm getting double miles on car rentals through the Visa.

If you're using an Amex, another option is to sign up for the premium coverage. I forget the cost -- maybe $25 per rental? I considered doing that but will probably stick with the Visa.

It looks like Visa may provide a marginally better deal as they stated that they will cover loss of use charges, if well documented. Amex preminum coverage is better but not available to NY, CA residents.

Can you shed some light on how to get double miles on car rental? UA cards seem to give only 1 mile per dollar spent. Is that a special promotion?

At the leaast the German Amex CDW does not offer you, if you have any kind of CDW in the rental package, so here the Visa/MC CDW is better.

Can you shed some light on how to get double miles on car rental? UA cards seem to give only 1 mile per dollar spent. Is that a special promotion?

Yes, it's a promotion. I don't have the terms in front of me, but it was something like double miles for travel-related expenditures (other than at airlines) in the months of June, July, and August in excess of a specified monthly minimum. For me, the monthly minimum was $125.

I don't know whether it's appropriate to mention Visa promotions on an Amex board.... Wait, I know how to bring the topic back to Amex. I'm actually qualifying for a double miles promotion on a Visa that I've had for eight months, whereas I never qualfiy for promotions on an Amex that I've had for over twenty years!

does AMEX also provide the collision protection on the Citibank AAdvantage Amex card? Or is the protection thru Citibank?

What is AmEx "premium coverage" and where can I learn more about it and/or sign up?

What is AmEx "premium coverage" and where can I learn more about it and/or sign up?

See here (https://www152.americanexpress.com/fsea/travel/car_rental/product.do?source=search). Note that signing up will automatically trigger the $24.95 charge for each car rental you make thereafter. Some people report signing up, using the coverage, then dropping the coverage after the rental is over.

That is crazy $450 for a little scratch?? You can buff that out yourself.

Based on personal experience, AmEx will not cover you if you have any sort of 'free day' coupon. I rented a while back while overseas and used a free day coupon. Since I 'did not pay for the entire rental using AmEx' they refused to cover the damage claim. Of course I paid for as much of the rental that was out-of-pocket but they claimed using a free day coupon invalidated the collision damage waiver. Not sure if that is also true if one were to use $ off coupons, which are more common.

In the end my claim was reversed by a different division of AmEx as frivolous ($450 for a 1/2" scratch on the wheelwell that was probably there when I initiated the rental) but that is besides the point.

I now use Diners Club for my rentals - primary coverage anywhere in the world and costs under $100/year. Also gains me access to some airline clubs overseas.

Just know what is and is not covered before you venture out renting cars making basic assumptions that could be wrong.

As a U.S. cardholder, I used to always use AMEX for international car rentals. Now I only use my Visa Signature card. AMEX used to provide U.S. card holders with PRIMARY insurance coverage interntionally and excess coverage domestically. Now I noticed in recent years that AMEX appears to have quietly dropped the primary coverage feature for international rentals. In contrast, U.S. Visa card holders appear to still have PRIMARY coverage outside the U.S.

Within the U.S., AMEX appears better because the coverage is up to 30 days while Visa is only 14. Both insurance is excess. Overseas, however, Visa appears to offer 30 day coverage that matches AMEX and becomes a PRIMARY insurer while AMEX is not.

Also worth checking exclusions, before traveling. Visa appears to exclude rentals in Israel, Jamaica, Ireland and No. Ireland. (Not sure about AMEX). AMEX and Visa may possibly also differ regarding which vehicles are excluded from coverage as exotic.

It is also worth checking what insurance extras (if any) that any special rates might offer that one might be able to access through a professional organization. I just about exclusively rent from Hertz and Avis using special rates my car insurance company negotiated because the rate includes a guarantee from Hertz and Avis that my liability is limited to $5,000 if I damage/total the rental car, they guarantee I will not be charged loss of use and they even throw in complimentary third party liability coverage that would be my greater concern if I were involved in an accident.

See here (https://www152.americanexpress.com/fsea/travel/car_rental/product.do?source=search). Note that signing up will automatically trigger the $24.95 charge for each car rental you make thereafter. Some people report signing up, using the coverage, then dropping the coverage after the rental is over.

FYI. I just got an ad for this in the mail. There is also a $19.95 level of coverage that includes slightly lower maximum benefits.

More importantly, the AMEX policy regarding paying for the rental also excludes DISCOUNTS (e.g. AAA 10% CDP, etc.). This basically means that nearly every business traveler, and many leisure travelers worth their salt would be excluded! (Everyone on this board, right?)

I spoke to a rep today who confirmed this. However, I could not get a supervisor on the phone to confirm (waited 10 min and gave up) and I have not seen it in writing. If this is correct, AMEX should be ashamed of this deceptive practice.

Really, how many people a renting cars at the "rack" rate? And howdoes my 5% off savings affect insurance coverage?

FYI. I just got an ad for this in the mail. There is also a $19.95 level of coverage that includes slightly lower maximum benefits.

More importantly, the AMEX policy regarding paying for the rental also excludes DISCOUNTS (e.g. AAA 10% CDP, etc.). This basically means that nearly every business traveler, and many leisure travelers worth their salt would be excluded! (Everyone on this board, right?)

I spoke to a rep today who confirmed this. However, I could not get a supervisor on the phone to confirm (waited 10 min and gave up) and I have not seen it in writing. If this is correct, AMEX should be ashamed of this deceptive practice.

Really, how many people a renting cars at the "rack" rate? And howdoes my 5% off savings affect insurance coverage?
My rental car was damaged when someone tried to steal it, unsuccessfully. I paid with a SPG AmEx. So far there has been no reason to think that things will not work out satisfactorily, with AmEx covering the entire $240 or so loss, which comes in below the deductible with my primary carrier. Hopefully, it will all be resolved without hitches. What has been said in previous posts, however, gives me much insecurity where AmEx is concerned.

AmEx always seeks to convey the impression that they are the "quality" product to rely on, but not so good if one has to distinguish between renting in US vs abroad; worry whether the rental will be treated as other than a fully-paid one; be uncertain if the coverage will be primary or secondary, etc. Doubts like these undermine the ad pitches, even if things work out for me in the current situation.

My rental car was damaged when someone tried to steal it, unsuccessfully. I paid with a SPG AmEx. So far there has been no reason to think that things will not work out satisfactorily, with AmEx covering the entire $240 or so loss, which comes in below the deductible with my primary carrier. Hopefully, it will all be resolved without hitches. What has been said in previous posts, however, gives me much insecurity where AmEx is concerned.

AmEx always seeks to convey the impression that they are the "quality" product to rely on, but not so good if one has to distinguish between renting in US vs abroad; worry whether the rental will be treated as other than a fully-paid one; be uncertain if the coverage will be primary or secondary, etc. Doubts like these undermine the ad pitches, even if things work out for me in the current situation.

Please keep us posted on how this works out for you.

It really does depend where you rent the car. The CDW isn't primary, so it will only kick in if they can't get the coverage from somewhere else.

It really does depend where you rent the car. The CDW isn't primary, so it will only kick in if they can't get the coverage from somewhere else.

Only reason I still have my Diners Club card: the CDW is primary, even in the US. (and I got the $95 annual fee waived)

Only reason I still have my Diners Club card: the CDW is primary, even in the US. (and I got the $95 annual fee waived)

You might want to check the other cc forum for complaints FT'ers have about DC customer service related to this. Seems DC is not what it used to be (as with AMEX, and the rest).

Only reason I still have my Diners Club card: the CDW is primary, even in the US. (and I got the $95 annual fee waived)

Good point; I recall reading this somewhere else. People who use Diners rave about the card for a host of reasons. I keep meaning to look into the card: I will this afternoon.

Good point; I recall reading this somewhere else. People who use Diners rave about the card for a host of reasons. I keep meaning to look into the card: I will this afternoon.

As I said, primary CDW is the *only* reason I still have the Diners Club card.

The rewards programs has been "enhanced" (i.e. no more transfers to UA and CO and some other ones). There has been more negative changes as well.

The one nice thing is I can transfer points to anyone (but not to that many programs anymore).

Visa offers primary coverage if you have any of their business cards. This coverage is good in the US and abroad with the exception of a few countries.

Visa offers primary coverage if you have any of their business cards. This coverage is good in the US and abroad with the exception of a few countries.

Check the fine-print though. If it's anything like the business MasterCard, it's valid only when renting for business. Whatever that means.

Check the fine-print though. If it's anything like the business MasterCard, it's valid only when renting for business. Whatever that means.
Interesting that there may be this advantage to a "business" card over a "personal" one. I have asked, and am still waiting for an answer, how "business" and "personal" cards differ in any way(s) consequential to me. This possibly better car rental coverage one may be such, though an "only when renting for business" restriction could effectively cancel out that potential advantage. (Yes, what exactly does only "when renting for business" mean, especially for the self-employed without a fixed tour of duty or duty station. And would they deny coverage if a loss occurred during a resort trip with the family? If denied that "primary" coverage, would there still be "secondary" coverage?)

A Overseas, however, Visa appears to offer 30 day coverage that matches AMEX and becomes a PRIMARY insurer while AMEX is not.

After a couple of calls to AMEX rental protection, I was told that the standard coverage does become primary, if, for example, your own personal rental insurance doesn't cover you outside of the US. This is not to be confused with the $25/rental Premium Rental Protection which is automatically primary and has a few more bells than the standard coverage. :shrug:

All forms of insurance that are secondary become primary if there is no other payor.

It is true that most standard US auto insurance policies only provide coverage in the US and Canada.

After a couple of calls to AMEX rental protection, I was told that the standard coverage does become primary, if, for example, your own personal rental insurance doesn't cover you outside of the US.

After a couple of calls to AMEX rental protection, I was told that the standard coverage does become primary, if, for example, your own personal rental insurance doesn't cover you outside of the US. This is not to be confused with the $25/rental Premium Rental Protection which is automatically primary and has a few more bells than the standard coverage. :shrug:
Perhaps some of this depends on the practical meaning of "primary." When the coverage is "secondary," it doesn't pay until one's personal auto coverage has paid all it is obliged to according to the terms of that policy. The "secondary," however, may wind up paying everything and the primary nothing. (It is my understanding that if you have $200 in damages and a $250 deductible on your personal policy, then the "secondary" coverage pays $200, the "primary" nothing.)

I don't know what one gains by paying $25 for "Premium Rental Protection." If someone thinks that is money well-spent, I would be interested to hear why. My big concern, as I expect is that of others, to know that I will be gapped or left totally unprotected under any circumstances.

I don't know what one gains by paying $25 for "Premium Rental Protection." [...] My big concern, as I expect is that of others, to know that I will be gapped or left totally unprotected under any circumstances.

Well, according to this Amex page (http://www133.americanexpress.com/osbn/landing/insurance/pr_carrentalprotection.asp), it covers:


Premium Car Rental Protection
Up to $100,000 in protection and up to 42 consecutive days of coverage with a flat $24.95 premium per car rental†

Automatic coverage for yourself and your passengers when car rental is charged to an enrolled Business Card

• Up to $100,000 for theft of or damage to the rental car

• Up to $100,000 for accidental death (up to $10,000 for a passenger)

• Up to $15,000 per person for medical expenses

• Up to $5,000 per person for theft of personal property


So some those are additional coverages, and it applies for slightly longer rental than the default (free) plan. However, it doesn't seem to include the one coverage that would seem important to me--liability coverage for damage to other cars/property. Within the US and Canada, standard auto policies generally cover that. Outside of the US, though, that's not the case. Rental cars often include some very basic liabiity protection, but it varies widely from country to country (and within the US, state to state).

I don't know what one gains by paying $25 for "Premium Rental Protection." If someone thinks that is money well-spent, I would be interested to hear why. My big concern, as I expect is that of others, to know that I will be gapped or left totally unprotected under any circumstances.

Another beneift of having AMEX as primary is that an accident should not increase you auto insurance premium, assuming the auto insurance company would have no involvement in the claim.

Well, according to this Amex page (http://www133.americanexpress.com/osbn/landing/insurance/pr_carrentalprotection.asp), it covers:



So some those are additional coverages, and it applies for slightly longer rental than the default (free) plan. However, it doesn't seem to include the one coverage that would seem important to me--liability coverage for damage to other cars/property. Within the US and Canada, standard auto policies generally cover that. Outside of the US, though, that's not the case. Rental cars often include some very basic liabiity protection, but it varies widely from country to country (and within the US, state to state).
Years ago, when Boston was in a real economic slump, I rented a Jaguar for a day at an unbelievably low rate. Other than one that occasion, I don't know when I have rented anything with a value >$25K. Coverage up to $100K for theft or damage to the vehicle is thus about as meaningful to me, and I expect most others, as would be coverage up to $500K, which is to say not at all. The other elements I don't know about, because I am less sure how much of a change they represent from what I can expect through my own coverage and that which comes with other cards or AmEx without the supplement. I am skeptical, in part because the car rental companies with their insurance schemes caused me to be years ago. And I find the caveats about how coverage might vary domestic vs international and under other circumstances disconcerting. When we go to rent for much of month long stay Down Under, I will give this more attention.

My employer is telling me that if I get their corporate AMEX card, it carries PRIMARY CDW for official corporate travel at no additional charge. I suspect that in fact it is either secondary, or it is primary using a variation of the $24.95/rental plan. We are not a big firm (230 people) so we wouldn't be getting any special breaks that a Fortune 1000 firm would get.

Realizing that each corporate contract might be different, does anybody here have a corporate AMEX with free primary CDW? If so, what car classes does it include, for example does it include mini-vans and standard SUVs (Explorer/Trailblazer)?

Realizing that each corporate contract might be different, does anybody here have a corporate AMEX with free primary CDW? If so, what car classes does it include, for example does it include mini-vans and standard SUVs (Explorer/Trailblazer)?[/QUOTE]

I decline CDW coverage for business rentals as it is a coporate policy to do so. My "business" rentals are covered when I use my coporate AMEX and also use my company code during the reservation process. If I get in an accident/situation I call my company first and they deal with the circumstances. I can't rent luxury vehicles under this coverage however the normal/common vehicles types are allowed though we're are officially steered towards reserving compact vehicles. I normally rent Outbacks, Minivans or SUVs.

Bummp..

I don't own a car and don't have any auto insurance. I am going to be renting a car in the USA for vacation. I have amex premium car rental insurance. They tell me all I need in excess is "liability" insurance. Does anyone offer this in the USA ? Thanks in advance...

I recently had an "interesting" experience with AMEX's coverage while renting overseas in England. Europcar had upgraded me to a Mercedes Avantgarde (not sure exactly what "class" that is, but it was a mid-sized Mercedes) and, sure enough, I ran over a nail and got a flat tire. The tire stores said the puncture (pretty small, actually) was too big to repair, so I needed a new tire. Given that it was a Mercedes, and given that I was in an expensive country, the price of the tire was $240. Europcar said I was on my own for tires but, fortunately, I called AMEX, got transferred to the US, and was told the repair would be covered.

I got home, filled out some modest paperwork, and was soon reimbursed for everything except around $35. I called to ask why, and was told the policy didn't cover tax (the UK charges a built-in 15% VAT). Surprised, I asked for a copy of the policy, which they emailed to me (I'd post it, but it's an email attachment).

Sure enough, the policy excludes tax. It also excludes other things, like damage to tires! I guess I'm not going to ask any more questions now. :) Other potentially troubling things it excludes is damage to vehicles worth more than $50,000. I had a brand new mid-sized Mercedes -- in England was it worth more than $50,000? I have absolutely no idea.

I saw the earlier posts about cars rented with discounts (like free day coupons) not being covered, but that seems wrong to me (I used to be a lawyer). The agreement says you must pay "for the entire rental" to activate the coverage. To my mind, amounts you "don't pay" (like discounts) couldn't logically be excluded, but if someone has really been hassled for this, it's obviously quite troubling.

While being out $35 is no big deal, my experience does raise some questions. What if I had totalled "my" new Mercedes -- or, perhaps even more likely, it had been stolen? What if the car had been worth more than $50,000? Would I have been liable for the whole thing? Or perhaps 15% of that? Obviously, on a few thousand dollar repair (easy on a Mercedes), 15% would add up to "real money." And am I likely to be out of luck on tire repairs in the future? And does all this mean that maybe I should decline the upgrade to really expensive cars (like Mercedes)?

The last option seems disappointing (who wants to turn down the Mercedes?), but I do wonder if prudence necessitates it.

While I'm new to FT, I have researched the CDW topic a bit. I'm sure some of the FT veterans can fill in the gaps or correct me on this, but here is my two cents:

(1) For the VAT, technically that is excluded in the T&C for AMEX CDW (as you mentioned). Now, you may have an argument to file to reclaim that VAT, you may have to do a lot of talking since you aren't actually bringing the tire back with you. Also, I believe I have read another post whereas the rental company may be able to reclaim the VAT on your behalf, although I doubt they will bend over backwards trying to work this for you. Bottom line -- one of the things in life we are assured of...death and taxes, and another way the rental agency can push the CDW/Super-CDW/etc. coverage.

(2) As for the vehicle value, I guess you could plug (a) the Diners Club card which covers up to US$75,000, (b) The DC Carte Blanch Card which covers up to US$100,000 (although nearly 99% of FT'ers scauff at this card, and arguably, rightly so), or perhaps (c) the "Premium CDW Coverage" AMEX provides for US$24.99/rental which covers you for US$100,000 and up to 42 days rental (and a bunch of secondary coverages like medical and personal effects, etc.).

As a final note, I'm surprised that they covered the tires, as you already mentioned, they are specifically excluded in the T&C. Although, I don't know if card type influences their decisions, if a nail in the tire is "optionally" covered and considered damage since it is a road hazard as opposed to a random "blow out" which would most likely be considered "wear & tear" which is also excluded, or if it was just a fortunate anomoly.

I do think this points out a very realistic issue for those who get upgrades to vehicles who may have an MSRP over US$50,000.

NOTE: As I'm writing this, I realized I didn't do a search before responding. Please forgive me for not searching before posting this if the information is in other posts.

Awhile back here, I mentioned an experience renting from Thrifty in SanDiego with AmEx and having the car damaged by a would-be thief. I was going to relate how it all turned out in the end. The answer is unhappily, because I was stupid. I thought I had used my Amex card, when in fact I had used my Platinum Visa. After AmEx turned down the claim ($240), rightfully so, and I learned of my mistake, it was too late (beyond 45 days) to get it taken care of by Visa.

I'm chagrined, but thankful more money wasn't involved. In the future, I'll pay more attention to what card I pull out of my pocket, and act promptly in case of a loss. (45 days can go by fairly quickly, at least for me.)

I will be spending 1 month OZ and NZ. Will one card or the other (or still another) be better for renting there?

I will be spending 1 month OZ and NZ. Will one card or the other (or still another) be better for renting there? US-based card holders renting in AU and NZ need to be careful -- over the last couple of years, several credit card companies' insurers have either dropped coverage or now use ways to reject claims from rentals in AU/NZ ...

For example, US Diners Club insurance for both their charge and credit cards now explicity mentions that:

You may be unable to receive benefits in Australia, Ireland, Israel, Italy, Jamaica, and New Zealand.

What can happen when you file a damage claim for a NZ rental is that the US credit card insurers will reject the claim allegedly because you "didn't decline the equivalent of CDW coverage". If you think you'll just "decline CDW" on your NZ rental, you could be in for a surprise ...


Getting a claim rejected can happen even if you declined everything you could decline on the NZ rental car contract, i.e. you declined buying "excess coverage". In NZ, the form of rental car contracts is specified by law and included in the contract is insurance for damage over a certain point. Below that is considered "excess" (the US term would be "deductible") and you may opt to buy or decline to buy "excess coverage" to cover your liability for that amount. However even if you decline "excess" coverage, the NZ rental contract includes some standard coverage for damages that you can't decline. While you could decline that coverage *theoretically*, in actuality you cannot -- There's no place on the standard rental form to decline that base coverage, it's already built into the price, and no mainline company would rent to you if you tried to decline it.

So a reasonable person would think CC insurance companies would be happy because they would only have to cover damages up to the maximum amount of the "excess" that the CC holder declined buying "excess coverage" for. But no, some of them now refuse claims from NZ rentals because even though the cardholder declined the excess coverage, the cardholder didn't decline the base rental car insurance that's on the contract (mandated by law) and that has no option to decline it!

I was rear-ended while driving a rental car in NZ and filed a claim with DC's (old) insurance company. They rejected the claim even though I declined excess coverage. It took around 9 months of protests and appeals before I finally got them to pay the claim. When they finally did pay the claim, I got the impression it wasn't because they agreed it should be covered, but rather because DC was switching insurance companies and they wanted to close out the file.

Diner's Club new insurer now explicitly mentions that rental coverage is not guaranteed in NZ and AU. (The old one mentioned Ireland and Israel, but not NZ/AU). "Automatic primary coverage, anywhere in the world" -- yeah right!

I have yet to get a straight answer from Amex's insurance company on NZ/AU rentals.

Definitely listen to Quokka, it seems the CC companies and rental agencies are getting very nit-picky lately. As for the card, I would assume that Visa would be your best bet in this case as it only excludes Isreal, Jamaica, Ireland, and Northern Ireland. AMEX states in its T&C that it will not, and Mastercard and Diners Club say that you may not be able to get benefits.

Best bet is to specifically contact the insurance underwritter/insurance section of your CC and specifically ask what you need to do to get coverage, and if they will provide it. Then ask the rental car agency if they will accept that coverage and if there are any stipulations. I know those who rent cars in Ireland now have a new dilema as of 1 September 2006 as Platinum Mastercard no longer provides coverage -- only World Mastercard and Diners Club (as they both use MC ASSIST for their CDW coverage).

Anyway, for US Visa Signature cards, as of 3/1/2006, they will cover you in NZ as long as you "...decline the rental company's CDW/LDW, or similar provision..." The point that Quokka mentions above regarding built-in insurance should be posed to the CC company.

Thanks Quokka and IloveMI. I never would have imagined such issues with the use of CCs to rent in AU or NZ, and I have seen mention of them in tour books either. If it were a car rental in some place like Uzbekistan, it might not be so surprising, but I don't understand why there should be problems in some of the places cited in this thread. Does this mean that one might have to pony up for the additional coverage which costs so much?

Does this mean that one might have to pony up for the additional coverage which costs so much?

Not necessarily, but you really need to read and understand your CC's coverage. You should call your CC's insurance department and have them spell it out for you what you need to do. Some companies require you to decline three different coverages (CDW, LDW, and one other I can't remember at the moment). Also keep in mind some exclusions: sometimes taxes and/or VAT will not be covered, perhaps not a big deal, unless you total a vehicle and have hundreds or thousands of dollars in taxes. Tires, arguably the most likely risk, is typically not covered by most CC's (although some folks have been able to get their cards to cover that). Another thing, not all coverages are the same. Some will specifically state that they cover towing and "loss of use charges" (varified by a fleet utilization log). This also doesn't even begin to touch on any possible claims process where you need to provide a great deal of information and all within a short period of time (typically 30-60 days). Without sounding synical, CDW through your CC can be a great way to reduce cost if you are in a low risk situation. It's up to you, but the car rental agency's insurance can really add up and turn a great rate into and expensive rental. An optional route is trip insurance. Some general trip insurance policies also add car rental coverage (although most cap out at US$25k-$50k, and could be an alternative...if you were planning on getting trip insurance anyway.

Even if you take the car rental company's insurance, you might still not be covered for tires. It seems almost universally excluded. While it's kind of a "gotcha" thing, the good news is that tire repairs on fairly-new rental cars are pretty unusual (I've had 3 in a few hundred rentals; all overseas, and only my latest while driving fully paved roads). Most of them can be patched for a few dollars. So while I might switch from one credit card to another for tire coverage (does mastercard or visa specifically cover it?), I certainly wouldn't buy extra coverage for this modest risk. A $240 Mercedes tire in Britain is certainly a "worst case" scenario.