I took my spare today and put it next to my wheel with new yoko tires. I found out that my tires 2 inches bigger. Around that. I was wondering how this would affect a final of 4.1 in my 89GXL. I hit 140 pretty easy now but with bigger tires wouldnt i be going faster than the speedo says??? Also i dont pull in 5th at all.

 

try this: www.prestage.com/carmath/calc_gears.asp

 

Wow. thnx... that was very usefull. exactly what i needed.