ok i hope this doesnt starta flame. but i had 275/60 on my back.. but i had to get new tires.. but the 1's i wanted i needed 17" rims, so im saving.. so i got soem cheap 235/60 tires (same as front) but it now seems that when i floor it i accelerate a hell of a lot faster then when i had my 275's.. is this normal??

 

Aziroc,
If I am thinking corectly, it may only seem that way. Smaller tires will spin faster than bigger ones, so will your engine. It may **seem** you are accelerating quicker, when infact, it is only your engine moving faster.

My geuss.

 

Bigger tires only help with initial traction, after you are hooked up they slow you down. First, they weigh more and require more horsepower to rotate, second the wider they are the more rolling resistance. Taller tires also give you less gearing and thus less acceleration. The last factor may or may not be an issue in your case, but the more flexible sidewalls like a bias ply tire/typical drag slick/BFG drag radials (not Nitto DR's) introduce much more rolling resistance and will slow you down if you don't need that much tire. When stock my old 97 Z consistantly lost 2 mph on slicks but gained .2 seconds in the first 60' then netted about the same ET???

The moral is to use the smallest tire you can hook up on.

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87 Formula 350 14.81@91.64
98 Z28 1LE 13.15@107.59

[This message has been edited by 98_1LE (edited July 29, 2000).]

 

Tire diameter produces the exact same effect as gears. Smaller tires = more gear. You may have just done the same thing to your car as going from 3.23s to 3.42s, or whatever; the car may in fact accelerate more as a result.

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"So many Mustangs, so little time..."

 

I heard on horsepower tv on tnn that for every inch increase in diameter you lose .10 in your gears. For example if you have 3.42 gears and put on tires that are an in. taller you will actually have a 3.32 gear ratio. I think that's what they said, it's been a while. Hope that made sense.

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1986 Berlinetta 2.8L, 700R4, 3.42 rear end
No major mods
Car was for sale
Damn tranny went out again so I can't sell it now