kwp Report post Posted April 7, 2015 Like others have said, if you didn't recalibrate your computer for the new tire size then all calcs are off (speedo, odometer, and mpg). With the bigger tire size you are traveling further than the truck thinks so your loss in mpg is actually not as bad. 1 Share this post Link to post Share on other sites
Explorer Report post Posted April 7, 2015 You need to change your diff gears if you go more than two sizes above stock tires. Otherwise you end up with a cool looking truck that needs a new rearend or even transmission. 1 Share this post Link to post Share on other sites
lancetkenyon Report post Posted April 7, 2015 You need to change your diff gears if you go more than two sizes above stock tires. Otherwise you end up with a cool looking truck that needs a new rearend or even transmission. This blanket statement is a little misleading. Totally depends on the truck, transmission, and axle combination. No way going from 31s to 33s on a stock Ford F250, Chevy 2500, or Dodge 2500 will trash an axle or tranny. Probably just about any other 1/2 ton or up either. On an old Jeep YJ/TJ/XJ with a Dana 35 rear axle, maybe. But those old C-clip axles can bust a ring gear with stock 28s on them. And regearing one is a waste of money if you actually use 33" tires for where they will take you. I have seen SO many D35s blow up it is ridiculous. If going up 2 sizes of tires blows a tranny, you have other issues. 3 Share this post Link to post Share on other sites
Explorer Report post Posted April 7, 2015 You need to change your diff gears if you go more than two sizes above stock tires. Otherwise you end up with a cool looking truck that needs a new rearend or even transmission.This blanket statement is a little misleading.Totally depends on the truck, transmission, and axle combination. No way going from 31s to 33s on a stock Ford F250, Chevy 2500, or Dodge 2500 will trash an axle or tranny. Probably just about any other 1/2 ton or up either.On an old Jeep YJ/TJ/XJ with a Dana 35 rear axle, maybe. But those old C-clip axles can bust a ring gear with stock 28s on them. And regearing one is a waste of money if you actually use 33" tires for where they will take you. I have seen SO many D35s blow up it is ridiculous.If going up 2 sizes of tires blows a tranny, you have other issues. Not trying to mislead anyone. There are lots of factors yes, you can drive any combo you want if its just a street queen truck. But get into heavy offroading or try using your overdrive and things start weakening. A truck with a standard is a little more forgiving. 2 Share this post Link to post Share on other sites
bonecollector Report post Posted April 7, 2015 I did a 6" lift with 35's on my F150 and within 2 weeks I had a photo radar ticket for speeding. I ended up getting a programmer to correct tire size and fix my odometer. 2 Share this post Link to post Share on other sites
Whitesheep Report post Posted April 18, 2015 Personally I try to to level my '04 Cummins Ram by carrying a bull elk in the back. To bad it doesn't happen very often. When it does I really don't care about the fuel mileage. 2 Share this post Link to post Share on other sites
