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15" or 16" wheels for road racing?

Old 12-28-02, 07:04 PM
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Question 15" or 16" wheels for road racing?

I'm running 7500 rpms around some tight combination turns on the track and it isn't worth shifting because I'll have to down shift 1 second later. I was thinking about getting 16" wheels and tires to raise my gear ratio. That would let me carry more speed thru these turns without shifting. I'm very close to my traction limit already so I don't need much more speed but a little more always helps. I heard that taller & wider rims could also slow me down because they are heavier and have more friction and are less aerodynamic. What do ya'll think?
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Old 12-28-02, 07:46 PM
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i doubt you will lose much power if you go with 16's also its better to have the extra traction
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Old 12-29-02, 09:59 PM
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I think you need to stick with what you have if you want to remotely stay legal within IT. I know your current class doesn't restrict you, but if you ever decide to run at any other race track with SCCA or NASA, you're screwed with a 16" wheel.

the 15x7s are fine traction wise for the power levels that ITS allows..

As for rear gearing, as I said to you in the other thread, tire choice isn't going to make dramatic changes in gearing, you're better off moving to a 4:30 or 4:44 or even a 4:88 or 5:12 rear gear. Use the gear calculator here: http://www.f-body.org/gears to determine how this will work for you.

You're close to your traction limit now because of the tires you're running, not because of the wheel size you're running.

Anyway, good luck beating RPV, he's going to be tough to stop

PaulC
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Old 12-29-02, 11:48 PM
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Unless you are going to get a license, and race in IT/PS1 in the near future, I would recomend you get what ever you can lay your hands on with the biggest contact patch, and the stickiest compound you can afford. Just as in HP, there is no such thing as too much traction. You will find that if you follow IT rules in preparing a car to race recreationally, you will be slower than your peers who are simply trying to prep their car to be fast at the local autocross. I would suggest 16x7 TII, or 16x8 FD rims(need spacers) with 225-50-16 RA1s, or V700s. Both rim sizes are readily available, reasonably priced. The key to all of your questions is whether you are building a dedicated PS1 car, or a fast car for use at the local autocross, and race track. If your building a gutted, all out PS1 car, folow Pauls advice, if you want to go as fast as possible for a reasonable sum of money, come to the dark side (more HP, more traction, more fun) with me Carl
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Old 12-30-02, 11:57 AM
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Paul, I saw your videos, great car and great driving. I'm new to road racing and have alot to learn and alot of improving to do on my driving skills. As long as our local track dosen't require us follow SCCA IT specs and they have people who are not worried about traveling to another track that does, it's going to be hard to keep up with them. So I'm not worried about changing my wheel size because I can always swap back to the 15"x7"s if I need to.
When I said that I was close to my traction limit I meant that I didn't have enough speed to reach the limit( I'm above redline 7500) without shifting, But if I shifted It felt like people caught up with me and that I would lose momentum for the next straight away. Taller wheels and tires are only for getting a little more out of 2nd gear. What is the stock rear gear ratio on a 87 n/a?



Originally posted by Silkworm
I think you need to stick with what you have if you want to remotely stay legal within IT. I know your current class doesn't restrict you, but if you ever decide to run at any other race track with SCCA or NASA, you're screwed with a 16" wheel.

the 15x7s are fine traction wise for the power levels that ITS allows..

As for rear gearing, as I said to you in the other thread, tire choice isn't going to make dramatic changes in gearing, you're better off moving to a 4:30 or 4:44 or even a 4:88 or 5:12 rear gear. Use the gear calculator here: http://www.f-body.org/gears to determine how this will work for you.

You're close to your traction limit now because of the tires you're running, not because of the wheel size you're running.

Anyway, good luck beating RPV, he's going to be tough to stop

PaulC
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Old 12-30-02, 12:32 PM
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Hey Carl. I guess i'm on the dark side with you until I decide to cross over into SCCA. The car is completely gutted and is for racing only.If I do any mods that can't be reversed easily/cheaply i'll have to decide then what way I want to go.
I'm still interested in your rims and tires. Can you take a picture of them and send them to me. I was told that a 1/2" increase in over all diameter is good for dropping about 500 RPMs. Does that sound about rite to ya'll.
Brett
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