The following was posted in a different thread, and I didn't want to jack it so I thought I'd ask separately: are there any actual mechanical benefits to recalibrating your speedometer after increasing tire size/changing gearing? I found this link where they claim benefits to mileage, reduced wear, better shift points, etc. Do you guys think these claims are legit?

Quote
Something else I forgot to add. If and when you change to a bigger tire, your speedometer and odometer will be off.

I used a TruSpeed Speedometer Recalibrator.

[Linked Image]

It corrected my speedo when I went from 31" to 33". If I decide to go up to 35" tires I can adjust again to correct the speedometer without extra expense.

99 XJ, 4.5" RE lift, SYE+driveshaft, 31" BFG ATs, Warn rear bumper+tire carrier, JCR front bumper and sliders