16" or 17" better for autocross???

[escapedan]

I cant seem to decide which rim/tire size is better for autocross - 16 or 17. My feeling is that the 17" will not have enough sidewall flex and will actually provide less traction. Am I totally wrong??

My suspension is tokiko illuminas w/ tokiko springs, energy susp bushings all around & rear swaybar. Any suggestions?? Any good places to get rims / tires??

Thanks a million!!

[Victor Laury]

Smaller is better!

Contrary to modern style, If you could fit 13'' wheels on your Z, That would be the best size for AutoX!

14X7 of the Lightest possible wheels running 195/55/14 DOT race rubber - about the same diameter as 185/60/14's but wider. and your ready to throw down

[escapedan]

SWEET! Thank you very much....I almost made an expensive mistake going with too large a wheel. This forum is awesome!! I would be totally lost without it!

[texasz]

I'm curious about this. Can someone explain why smaller is better? I know bigger is not always better but in this case why is smaller better? I was thinking that a good light 15" would have been better than the 14" that is on the car.

[Victor Laury]

Tire diameter isn't a concern in autoX. You don't spare any time filling the wheel well. Smaller diameter lowers your ratio. combined with lower weight it's a win win. Who cares if you speedo reads correctly? Your too buisy and it's bouncing around too much to read it anyway.

True, there's some fantastically light 15'' race rims out there. In our offset, you'd be hard pressed to find them. My 15X6 revolutions on the roadster are boat anchors when compared to my 14X6 AR Vectors at 11lbs a piece.

Some of the Miata crowd change at the track to a set of feather weight SSR 5 spokes that almost float out of your hands. Find those in 0 offset and you scored!

[texasz]

Originally posted by Victor Laury

Some of the Miata crowd change at the track to a set of feather weight SSR 5 spokes that almost float out of your hands. Find those in 0 offset and you scored!

Is SSR a brand name? Are you talking about 14 or 15 SSR wheels? Where might I start to look for a pair?

[escapedan]

Regarding the offset....I am now going to go out and grab a set of 14x7 per your suggestion, but what do I need to look for in the offset? Thanks again!!

[2ManyZs]

With a 7" wide rim, the best offset is 0.

Larger wheels above 15 inch will require larger brakes and a lot of suspension upgrades, or it's a waste of money.

[Gav240z]

So let me get this right, bigger wheels allow for bigger brakes.

Smaller wheels mean less unsprung weight and therefore more time with the wheels touching the road = more traction?

So while bigger wheels look nice they don't neccessarily improve performance of a car.

I always thought people put bigger wheels on for fitting larger brakes(you also get the people who do it for looks).

Can anyone explain why too wide a tyre is not good? Does it slow you down by causing too much friction?

Also do smaller wheels mean your turning less wheel and more power goes to the wheels than say with a bigger wheels.

Ie Torque = Force X Distance?

Alot of questions but really would like to know.

This brings me back to another question regarding the toyota 4x4 calipers I went to a toyo wrecker who said that i would loose the advantage with the increase in weight(unsprung weight), This is one reason I haven't gone ahead with this conversion just yet.

:cheeky:

[260DET]

Smaller wheels also lower the car. Drive there with your larger road wheels/tyres, change to your smaller wheels with race rubber. One bloke I know does this, tows a small trailer with his race wheels in it.

[2ManyZs]

As far as the weight difference betwen the Toyota calipers and the stock ones, I can hardly tell the difference. I just got a set of the S12's and holding them in one hand and a stock caliper in the other, I can hardly tell a difference in weight. I don't have a good scale to weigh them on, but the difference is not as big as you would think.

The body of the caliper is larger, but the pistons are so much smaller in the Toyota calipers, that I think they would actually come out pretty close in weight.

[260DET]

One thing to consider when fitting Toy four spots to the front, or any other four spots for that matter, is the potential effect of increased front braking power you will get, assuming that increase is not balanced by an equivalent increase in rear braking power.

Such an increase may in certain circumstances lead to front brake lockup. Not a good thing.