worldminer

I rented a vehicle from SGU Monday afternoon and very early yesterday I started a long drive into Nevada. I noticed the low pressure warning (still dark, instrument panel bright). I found a pay inflation station and filled all of the tires. They were in the mid twenties (30 recommended) but the front left had 24 pounds of air. I paid a dollar for the air so not really the issue. I called CS and was told that I was responsible for the tire pressure once I left the lot. Um, I'm more car savvy than most and recognized the warning light. However, the CS missed the point, why would Hertz rent a car without checking the tire pressure themselves? 24 pounds is pretty low.

Not looking for a resolution at this point, my learning experience cost me a buck. Perhaps a warning that you shouldn't depend on any one else's "pre-op" inspection other than your own. Lesson learned.

JMorgana

Call me petty, but after CS's response I'd escalate to Hertz's execs just on principle. I'd also consider switching companies given all of Hertz's recent issues.

anteater

I had a similar issue once. I rented a vehicle and while I was waiting at a red light I browsed through the dash menu to see the tires at 70+ PSI. I pulled to a local Costco and verified they were indeed at 200% pressure.

I spoke with the GM of the facility who investigated and found the person in charge of the air pressure unit had incorrectly set it. So for some period of time all vehicles at the facility were being washed, cleaned, and overfilled with air.

Sometimes things are an honest mistake.

garykung

No offense - but OP, I am more skeptical to you than Hertz in this case.

TPMS is a mandatory feature. So if the tire pressure is really that low when you rent it, it will signal for a tire pressure check.

Also - tire pressures fluctuate based on many factors, such as usage, temperatures, the kind of "gas" used, etc. And don't forget - tires lose air over time.

To give you some credit - I don't believe the tires were pumped at 30 psi at the beginning, may 1-2 psi lower, which would consider acceptable not optimal. But to say Hertz not doing necessary maintenance is an overstatement. In fact - you kind of expose your lack of automotive knowledge.

fastflyer

^ That seems riskier than a slightly underinflated tire. 70 psi must be close to the bursting point.
Hertz is definitely having challenges keeping its basic operation going during the pandemic. Not sure they were ever that good at tire pressure, but they often would call me during past rentals telling me it was time to change the oil (meaning bring the car in and they would do so).

Often1

For $1, I would not waste time on a call.

Say something when you return the vehicle and I bet that they knock $5 off the tab.

glostix

I've definitely noticed particular patterns at SFO on different cars of different makes, so it's clearly Hertz employees causing it.

Front right tire 39PSI and others 33PSI, or something to that effect. Clearly they were leaving the pump on that last tire the longest, while doing another task or something.

Frequently would get one tire like 12PSI higher than the other corners, strange stuff like that.

m907

Almost every car I rent is overinflated, between 40-50 psi. It seems like National does it as a matter of policy. But 70 is definitely way too high.

FlyinHawaiian

I added a pencil tire pressure gauge to my rental car kit (includes my GPS, cigarette lighter power brick, and toll transponder) after receiving too many cars with under- or over-inflated tires.

SixAlpha

Many tires, even when inflated properly, look a little low. You might be surprised at how rarely the rental companies check the pressures, and how frequently customers add air to the “low looking” tires. At many locations, the rental companies don’t perform their own oil changes/tire checks... it’s outsourced to local tire shops who frequently overinflate.

teddybear99

70 psi is nowhere near the bursting point as there are vehicles that require 80 psi to as much as 100 psi to handle the needs of the vehicle whether it be load (weight) or performance (handling) of the vehicle. The same exact tire may have different optimum psi on different vehicles as the weight of the vehicle may be greater than the other.

Tire Pressure can fluctuate as much as 2 psi while driving as when the rubber hits the road it actually heats the tires and air expands causing the psi to increase and will cool down after sitting for a period of time. Over a month period all cars will lose approximately 1 psi in the tires due to the heating and cooling of the tires, so you should even check your own personal car's pressures at least once a month and should be done when the car hasn't been driven too long as the door frame will tell you what the vehicle's cold psi should be. Also don't rely on the number shown on the dashboard as it can be off by as much as 2 psi and the warning light is programmed to only illuminate if there is more than a 10% difference (high or low) of the pressure programmed into the ECM.

Hertz is a national account with Firestone, Tires Plus, and Wheel Works. You can always drive in and request a free tire pressure check and they will verify the pressures in all tires as well as inflate to proper pressures for free. You don't need to pay for any air.

anteater

Tires are manufactured differently depending on well.. the manufacturer, tire size, and intended application.

In my case it was a sports car with Michelin tires with a razor thin sidewall. Being at 200%+ PSI was certainly a burst hazard given that there is minimal sidewalk to flex if I hit a pothole.

teddybear99

Being in the tire business, I will tell you that the sidewall on that type of vehicle is thicker than you think. 70 psi is not at all that bad as it will give you a harder hold while cornering and it only would "explode" if you were to curb the tire on a sidewalk or some metal sticking out of the sidewalk/curb/wall.

anteater

A vehicle absorbs energy through the part of the vehicle that encounters for it. For a pothole, as the example, the tire, wheel, and suspension absorb that energy. For extreme examples, look at Tesla Model 3 S with cracked rims. Those vehicles have ultra short suspension travel, low profile tires. In many cases, potholes are cracking the actual wheel and bursting the tire because the suspension could not absorb all of the energy from the impact.

The sidewall is more rigid yes, not thicker. The increased rigidity with decreased physical sidewall height created a stress problem when the vehicle encounters a situation such as a pothole — where the vehicle had reduced ability to absorb the energy from an impact it puts strain on the components of the system. For example, a sports care with minimal clearance and suspension travel will rely on the tire to absorb the impact, and given the increased rigidity of the sidewall and reduced sidewall height it undergoes much higher stress than other applications (eg a suburban with a thick sidewall tire).

An overinflated tire will also decrease overall and evenly distributed surface contact of the tire, which reduces both handling and stopping ability but increased the stress to the minimized contact point between the vehicle and the road. So, when the vehicle counters an absorption event the stress is distributed over less surface and more likely to cause a failure of the tire.

The fact is that an over inflated tire can burst due to a pothole. It can occur with increasingly likelihood if the suspension is tighter or shorter travel (eg sports car), if the tire has a short sidewalk (less ability to absorb and dissipate energy), if the tire has already been subject to extreme stress (causes material to break down). In general, engineering standards build in a 10% overhead to stayed thresholds to ensure that end-users are less likely to accidentally break an item or cause early failures due to near-tolerance usage.

So, yes 200%+ PSI was unsafe. 😋

I recommend checking the tire pressure on your next Hertz rental by using the car’s onboard computer.

jim32190

Yeah because you are an engineer and know the physics of wheels and tires.

I’d believe the other guy, 70psi is pretty overinflated but if a tire can go from 25 to 50psi as printed on the sidewall, I’m certain there’s some overhead in case of overinflation so it doesn’t explode in their face.