Tire Size Change Question

[stryker6040]

Originally Posted by JackandJanet

You're not accounting for "squish". Try subtracting 3% of 2741 to get a more reasonable "loaded" circumference. When I do this, I get a value of 2741 - 82 = 2659 mm.

Unless you compensate for squish, your PCM will think each revolution of your wheels moves further than you are actually traveling. That equates to to a higher speed than you are actually doing. Try it with 2659. If you're still indicating faster than you're actually moving, reduce it still more.

Oh, and Lars was correct too. Make sure your Gear Ratio value is correct when you do this.

- Jack

Thanks for the info. i have never heard of the squish until you just brought it up but i guess it does make sense. Another thing I was wondering is what should I run in these for air pressure? I currently have 35psi in them they are procomp xtreme mt in lt315/70r17 i was debating putting 40psi in them but i dunno