Chevy High Performance
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Tire Size

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Tire Size

WScott WScott
New User | Posts: 40 | Joined: 03/12
Posted: 01/08/13
07:23 AM

i am currently running 26" tall tires on my car,since it is time to put
new rubber on it i was thinking of going to 28" tall tires,i am running
a 3.55 rear end and was thinking i may go to a 3.90 gear in the future,
if i stay with the 3.55 gears will there be much of a performance
difference between the 26" and the 28" tire sizes. Wayne  

76Skylark 76Skylark
Guru | Posts: 853 | Joined: 12/11
Posted: 01/08/13
09:12 AM

Wayne you would see it on the Tach at cruzin rpm but I doubt you would feel it in the seat of your Pants unless you only had 150HP then you would.  

68scott385 68scott385
Guru | Posts: 1990 | Joined: 10/09
Posted: 01/08/13
01:18 PM

With a given gear, you'll see about 200rpm difference at 60mph between 26" & 28" tires.

With a given tire, you'll see about 130rpm difference at 60mph between 3.55 & 3.90 gears.

I only used the tire sizes and gears you mentioned to come up with my numbers.

rpm = (168 x gear ratio x mph)/ tire radius...

...where gear ratio is the final drive number...if you have an o/d trans you would use rear gear ratio x o/d ratio to get the number to input in the equation...radius is 1/2 of the overall height of the tire  
68scott385 68scott385 68scott385