I went to have them reprogram my computer for my 35's and the guy did it for free just cause he wanted to see if he could do it. If you have this done, make sure to tell them to go in the "other" menu where you can enter any number of revolutions from 400-900. I entered 600 for my tires. So far, the speedo seems alright. I'm turning 1800 rpms at 70 mph and pushing about 7-8 psi of boost. I was running with the flow of traffic where as before I was flying through it at 70. So something is different. Just thought I'd give you guys a heads up.

 

Thanks for the info. I went from 265/75 to 285/75, and plan on going to 315/75 on next tire change. I still have not corrected mine, but now I know I can. I was told 285/75 was as big as they could go with the calibration.

 

You just have to tell them to go the "other" menu screen and give them the revolutions per mile. You can give them any number between 400-900.

 

You give them RPM for what speed, or doesn't it matter?
Rowland

 

What Big Blue meant to say was revolutions per MILE. Obviously, a larger tire will have less revolutions per mile than a smaller tire. The info for whatever tires you have should be in the specifications section of www.tirerack.com

 

The revs per mile for a BF Goodrich All Terrain TA is as follows:

285/75/16 - 632

35/12.50/16 - 600

315/75/16 - 599

 

Ya. What amartinson said. I got my specs from the BFG website. I figure that a 315/75/16 is a 315/75/16, no matter what brand of tire you have (I have Nitto's just for the record ). I had them enter in 600 for mine instead of 599 because I'd rather my speedo be reading just a hair fast than slow(although we're talking about .1 mph probably). More comfort zone from cops.

 

Do you find that the 285' or 315's give you higher milage treadwear then the standard 245's, like came on my '99?

 

I had 265's standard on mine and I only got 6k miles out of them. I was....ummmm.....hard on them. The next set of 305's I had lasted 20K miles. I wasn't to bad on them (Goodyear Wrangler AT/S: $800). The next set I got 35K out of (Dominator Sport AT's: $450). I've currently got a little over 1K on my Nittos. I've chirped them once. I'm proud of myself.

 

Big Blue DID say Revs per Mile...I just read RPM's. Got it now! Great Info-didn't know it could be done. Thanks to all!

Michelin shows 285/75/16's at 634 at 45 MPH. Think the revs goes down when going faster???
Rowland

 

Don't know about anyone else here, but my 2500 came with 17inch tires, not 75/16 tires. ....


The BFG 31570R17 revolutions per mile is 601, as per the tirerack or BFG web site.

315/70R17 121/118R D
3195lbs.
50psi
17/32nds
8.5-10"
8.5"
12"
NA
34.5"
601 revolutions per mile.

 

Actually, Dodge didn't start using 17" rims till 2003. Before that we all have 16" rims.

 

rjohnson

Revolutions per mile stays constant at any speed. It is independent of your engine RPM.

-CM

 

If that is true than isn't it curious that Michelin lists a specific speed for revs per mile. I thought maybe centifical force might make a tire bigger in diameter as the speed increases??
Just guessing.

Rowland

 

You are correct, the faster the tires spin, the bigger they get.

Think Top Fuel Dragster.

They start out as short fat tires, as soon as the driver punches it, they get really tall and skinny.

Regular tires don't grow that much, but they do grow.


phox