went autocrossing on 20" wheels. switch to 17"?
 

Hi fellas, I need some help please. I went to my first autocross event this weekend and I turned in great lap times including one fastest lap of the day time. I did that on my 20x9.5 and 20x10.5 heavy *** 3 piece wheels with 255/30/20 and 285/30/20.

I am going to attend more autocross events but I don’t want to continue burning through these tires as they are expensive. I have my oem 17” wheels (17x7.5 and 17x8) at home. Each wheel probably weighs 6-8 pounds less then my 20” wheels. Would it be better to run my oem wheels vs my 20” wheels? I understand that the weight difference will help but will I by losing something by going to a much smaller width wheel? I always thought that having such a large width wheel I would have better traction but after a little research I am beginning to think that it doesn’t matter. Will I lose something because my oem wheels do not have a flush offset and my 20” wheels do? Is any adv/disadvantages using a 17" wheels and 18" beside weight(considering somehow I find a way to afford new wheels)?

BTW I cant afford to buy new rims so I have to use my oem wheels or my 20” wheels. I appreciate any assistance including tips on things I am forgetting to take into consideration. Thanks.

hell yeah run the 17" instead, weight of the wheel+tire combine make huge difference.

It doesn't matter how wide your wheel is, it's all about how sticky are your tyres. You can stuff any mediocre 285 size street tires on there, but a good alignment and with 245 size good all summer performance street tire can put it into shame.

first thing first, how serious are you trying to get into autocross? If it's all about fun, just throw the 17" wheels back on and have at it. secondly, if you planned on advance your skill and get involve with your local autocross chapter, think about which class group you want to run. Most G with few bolt on can fit into STX, STU class under SCCA rule if you planned on running street tires. The winning tire is Bridgestone RE11 for both classes mentioned above.

From what I saw under your signature, if you want to run R-compound tires like Hoosier A6 or Khumo V710 then you can run in street prepared class.

good luck! regardless I don't think it's beneficial or wise to run 20" wheels in any sporting event.

Thank you for responding. Right now I am just doing it for fun but you never know I might do it more seriously.

So are you saying that in autocross it doesn’t matter if a wheel is 8” wide vs 10.5” wide? What if the diameter was the same (say 17”) then would the width matter?

If I stuck to stock sizes would going to an 18” make a differences vs 17”?

Do you know if there are any wheel size rules under stx, stuf?

Sorry for all the questions. I just have googled the ish out of this topic but haven’t found answers to all my questions.

The weight savings alone would be worth switching to your 17's, let alone tire prices. You might be able to run a wider tire on your 20's, but when each 17" wheel weighs 8lbs less, your gonna have an advantage over the 20's.

Max wheel width for STX is 8" but overall diameter doesn't matter. Max tire width is 245mm. If you're just going casually I'd just use your stock 17's.

The 17" vs 18" doesn't matter until you get competitive. 17's are lighter, generally cheaper and tires are cheaper. 18's are slightly heavier, more expensive, and the tires are more expensive, but the tire selection is better.

what he said, im switching from 18s to 17s this season just due to the savings on tire prices (and my engines basically stock just intake and exhaust). but 18 tire selection is much better