I purchased new tires yesterday on a whim. The couldn't stand the old.

The new tires are Dueler Revo AT's, 235/85/R16 load range E. So far, so good. I have only put about 70 miles on them.

They are 32.1 inches tall, Bridgestone says they turn at 649 RPMs.

The old tires were ProComp All Terians, 285/75/R16. Load range D, never will buy load D tires for a Cummins agian. These things were almost shot before I had 39,000 miles on them.

They are 32.9 inches tall. This is what the truck is currently set to run with. I don't know how many RPMs they turn at. The same size Bridgestone tire turns at 631 RPMs.

Should I expect my spedometer to be about 2-3 mph off?

Thanks,
Cjthor

 

yes, there is a 2 1/2% difference is size between your old and new. 3 mph off is expected.

 

Thats the reason the factory installs the E load range tire. I would never install a D rated tire on any of my trucks.

 

Plug in your tire sizes to see how far off your readings will be.

http://www.dakota-truck.net/TIRECALC/tirecalc.html

Looks like @ 60 mph you'll be 2.08 mph off.

 

I finally installed a set of e-range tires onmine. Went from 285-75-16 BFG's to a set of M-55 Toyos,same size. What a difference. Besides actually being a round tire,the M-55's handle the camper weight super. Really pleased. As posted a slight singing between 40-50 mph but nothing that these noisy suckers can't drown out.

 

You are doing it right by getting the E rated tires. The D are 8 ply and the E are 10 ply sidewall. A D rated tire may seem smoother but the heavy weight will push that tire and cause premature wear. If you are going to pull a trailer, or camper a E rated tire it a must. Plus there is a liability factor. All tire shops i know of in my area wont install a D rated tire on a truck that is Built with E rated tires just because of the liability. The way our courts and lawyers are any one who installs a D rated tire is leaving their selves wide open for a lawsuit in the event of an accident no mater if the tire is directly at fault or not.