Originally Posted by
djp98374
There was a stretch I saw on I-15 in Utah where I think it is 80/85... It's around the cedar city / beaver area
It's 80 in that approximately 20-mile stretch of I-15, but the OP won't be driving in that area.
Highest posted speed limit for the area the OP will be driving is 70 MPH IIRC. South of Las Vegas on I-15, I believe Nevada keeps that speed limit at 70 to match California's 70 limit. North of Las Vegas the speed limit on I-15 is 75.
Speed limits of 80 MPH currently occur in only two places in America: That small stretch of I-15 in southern Utah, and a stretch of I-10 in West Texas.
The highest posted speed limit in America is 85 MPH on a stretch of the Texas 130 toll road built as a bypass to I-35 for Austin.
Driving 5-10 MPH over the posted speed limit will almost never get you a ticket in America, except for a few Barney Fife types.