here is mine (damn, that shizznit got a f'ed up)


Stock Tire - 215/75R15 >Search Tires Tire 1 - 31x10.50R15 >Search Tires Section Width:8.46 in215 mmSection Width:10.51 in267 mmRim Diameter:15 in381 mmRim Diameter:15 in381 mmRim Width Range:5.5 - 7.5 inRim Width Range:7 - 9 inOverall Diameter:27.69 in703.32 mmOverall Diameter:30.97 in786.63 mmSidewall Height:6.34 in161.03 mmSidewall Height:7.98 in202.69 mmRadius:13.84 in351.53 mmRadius:15.48 in393.19 mmCircumference:86.99 in2209.5 mmCircumference:97.29 in2471.1 mmRevs per Mile:751.1Revs per Mile:671.6Actual Speed:60 mph100 km/hSpeedometer1:53.6 mph89.4 km/hSpeedometer Difference: -Speedometer Difference: 11.83% too slowDiameter Difference: -Diameter Difference: 10.6%

 

i got 30s on it now, i wouldnt worry about changing it till you get to 31s or bigger. soon as I get some bigger tires on I am going to change the sensor in the tc that tells the speedo the right speed.