metalliman

I have an 83 GSL with the stock 3.909 LSD rear end. I've strongly considered buying the 4.444 gears from mazdatrix but they want $463 for them.

Wouldn't a much cheaper alternative be, to simply buy smaller tires? Stock, I have 185/70/13 tires. Which calculates to a diameter of 23.2 inches.

185 * 0.03937 * .7 * 2 + 13 = 23.2

However, I can buy 175/50/13 Sumitomo High Performance Summer tires from tirerack.com for $39 a piece. There diameter calculates out to 19.9 inches.

175 * .03937 * .5 * 2 + 13 = 19.9

Wouldn't swapping these tires on have the same effect as having a 4.557 gear ratio?

(23.2/19.9) * 3.909 = 4.557

This would also lower the car roughly 1.6" without reducing suspension travel.

Would there be any cons to taking this route, other than making my car look a little funny with those tiny tires?

stinkfist

The cons will be a smaller contact patch, reduced fuel economy, and some funky wheel gap.
Switching to that tire will make your car accellerate faster but you will loose some top end.

Good luck,
MIke

metalliman

Well, I understand the cons associated to having lower gear ratios, such as reduced top speed, poor fuel economy and having to re-calibrate the speedo. But will the smaller contact patch significantly reduce traction?

That's one thing I never understood. Why does a smaller contact patch result in less traction. If traction (friction) is directly proportional to downforce, then this should cancel out this effect. However, I know that's not the case.

85rotarypower

The contact patch wouldn't be that much smaller. Not enough to seriously consider it a major con. The worst thing would be the fender gap. You would have aproximately 1 1/2" more fender gap. I think there is about 1 1/2" to 2" with the stock tires, you would be doubling the fender gap. This would make the car look "jacked up" . Kind of funny if you ask me.

hamster

adhesion goes as the contact area.

metalliman

So, other than my car looking funky, there are no other major cons. I guess my mind's made up, I'm probably going to get them little tires.

Thanks guys

honegod

a couple advantages to the shorter tyre are
reduced unsprung weight, and shorter sidewall which stiffens it, which helps turning.

NanaimoRx-7

I use a 185/60/13 Tire right now, feels pretty good. I still miss my 205/60/13's though. Can't wait to pick up some 13x7's and get back to some 205's.

BigJim

whats the deal with the 13's, everyone has them basically. I remember somethign about autox requiring max of 13, but does everyone here run autox, or is there some deeper meaning behind the 13s than autox

85rotarypower

If I understand what BigJim is saying, you must be living in a cave or something. The stock wheel size on a non-SE is 13". The SE had 14". They look bigger than they are on these small cars.

K-Tune

iTrader: (26)

well..it's stock on the car...so it just looks right

(i have 15"..lol still looks good!)

85rotarypower

Hey, I'm just saying that I hope BigJim knows what he is saying, if I understand it right. To me, his post means that he thinks that 13" rims are an aftermarket thing that we all go for because mabey they are better for autocross or something.

BigJim

I did know they were 13's, but when ppl were posting on here and on other threads i thought they were talking about 13 inch rims as an aftermarket rim that they bought, but it just never occred to me that they were only getting new tires

NanaimoRx-7

I'm talking about buying aftermarket 13" rims. No school like old school. Either some Panasport's if I come across alot of $$$ or some diamondracing wheels for track and (cough) perhaps some mild street use. I wish the diamonds were tough enough to take daily driving, I'd run them year round.