I bought a 2012 Dodge Ram 2500 Diesel back in January. I had the dealer swap out the stock tires with BFG AT KO 315/70/R17s D range (max 50 PSI) that I had on a 2007 Dodge 2500. When the dealer did this the computer went crazy. The TPMS light was on as was expected,
but a whole bunch of other problems popped up. The speedometer showed exactly double speed (measured with GPS), at 15-20 mph the abs light turned on, the traction control turned off and the cruise control wouldn't work.

Took it back to dealer, they said you can only run max 285/70/R17 tires with E load range of 80 PSI and that was supposed to fix all of the above mentioned problems. I bought the BFG 285/70/r17 tires and away I went. Well the speedometer is off 5-7 mph depending on speed, but that's not really a big concern as all of the other issues were resolved.

What concerns me is that I know people are running 315s on their Trucks without this issue. I thought well maybe it has to do with Tire pressure and I dropped all tires to 45 and did a test. As expected only the tpms light came on and everything was fine otherwise.

I still have the 315s, but would be looking at $60 to put them back on and see if the issue still exists and another $60 to take them off if they did.
Can someone provide some type of explanation as to why this happened or why a 315 vs a 285 would case the speedometer to be off by double?

Are any of you guys running 315s on a 2012 2500?
I need help please. I thought I had this issue resolved in my head, but I have the sweet 315s staring at me and from a logical standpoint the issue just doesn't make any sense.

 

I have 315s in the Bridgestone Revo 2s, I have had none of these issues except when my speedo said 70 I was going 76-77. Mine are rated to 65 psi so no tpms issues either.

 

Thanks for the reply. It's further validation that the tires should work.

 

Sounds Like the tried to Recalibrate your truck and that is a NO NO! I ran into this same thing; had them put it back and everything is OK.

 

Installed LT285/70R17 BFGoodrich All Terrain TA's on my 2012 Dodge Ram 2500. Tires fit wheelwell no problem. Adjusted air pressure to 60Lbs when no load is on truck and speedometer is dead on with GPS.