Tire Size 25.21?

[RichmondZ16]

Where does this HPTuners get this diameter number?

I have read my 2004 Z06 VCM into the software and done some tuning.

The Stock Goodyear Eagle F1s are 26.1 Inches. My wider Nittos are 26.3.

So now I know where all my speeding tickets have originated

After thinking this is silly, I had to run the numbers.

I am sure you guys have done or read all this stuff before, but what the heck :

63360 inches per mile
3,484,800 inches per hour = 55 mph
79.20 inch tire = 44000 revolutions per hour (what the computer is counting)
44000 * 82.62 = 3,635,280 inches travelled on the bigger tire
150480 more inches than on the smaller tire, or 4180 yards = 2.375 miles per hour (not enough to get a ticket, but at the margin)

[Throttle]

i dont understand the question measure your tire and enter it in the tire size and be done with it?

[Russ K]

My 2001 ZO6 also has 25.21 for the tire dia. You don't use the actual tire dia, but the loaded tire radius. Your Nitto tires are .0076% taller, so multiply the 25.21 by 1.0076 and that is your new tire dia.

Russ Kemp

[RichmondZ16]

Thanks guys, I realized what you explain here when checking the height by hand. Sorry I did not think of that earlier. Guess it makes sense that the vehicle weight cannot be assumed by the tire maker.