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GT86Bob

16 inch wheels with low profile tyres

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I am seeking better acceleration for hillclimb events and this thought crossed my mind. Wat do you think?

Get some 16 inch wheels (allowed in class as they were fitted to the Primo I believe) and put low profile tyres on them .

Will it work? I'm not saying I'll run it on the road with these fitted,  just in competition.

Cheers

Bob

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It will change overall gearing, but will look ugly, and will that ratio change be sufficient? Google some online tire calculator for change comparison between different tire/wheel sizes, to find out ratio of change.

If it's allowed by rules, isn't more common way to install different ratio final drive? (not suggesting close ratio gearset, as that's a bit too expensive).

16" that are installed in JDM/ADM lesser trims also were used with higher profile/sidewall tires, so that overall gearing ratio was still almost same.

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On 10/14/2017 at 10:38 PM, Church said:

It will change overall gearing, but will look ugly, and will that ratio change be sufficient? Google some online tire calculator for change comparison between different tire/wheel sizes, to find out ratio of change.

If it's allowed by rules, isn't more common way to install different ratio final drive? (not suggesting close ratio gearset, as that's a bit too expensive).

16" that are installed in JDM/ADM lesser trims also were used with higher profile/sidewall tires, so that overall gearing ratio was still almost same.

I don;t care about looks, this is just an option for the hillclimb. I'll change them before and after the event. I agree changing ratios is better but that is permanent and this is also my daily driver. I know 16s were fitted with higher profile tyres... I was thinking about the possibilities of 16s with low profiles to reduce the oevrall diameter and hence the gearing.

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I don't know about hillclimb, but optimal gearing ratio is very track specific. For example on some tracks higher gearing ratio may not mean better acceleration, but rather lost time due extra gear switches needed to stay in optimal powerband. Had i lot of money, my own choice would be installing both close ratio gearset (that makes 1st and 2nd gears "longer" on ours) + higher ratio final drive. This way i'd get similar to existing ratio of 1st and 2nd (especially speed range of 2nd seems very optimal for half of tracks i'm running at), yet better geared and more usable higher gears.

P.S. From what i recall reading in threads about changing FD, they doesn't impact daily driving in bad way too much to care a lot about cons. Yes, maximum speed will be reduced a bit (but unless one lives in Germany, does it matter?), yes, fuel economy may suffer a little bit (but not by much, rpms will be higher per set speed, mechanical losses a bit higher, but one needs less fuel per each higher geared rpm for needed power), and slightly noisier due cruising at higher rpms. But it looked like those cons were within acceptable limits for ones done that mod, and they were satisfied with doing it.

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11 hours ago, GT86Bob said:

I don;t care about looks, this is just an option for the hillclimb. I'll change them before and after the event. I agree changing ratios is better but that is permanent and this is also my daily driver. I know 16s were fitted with higher profile tyres... I was thinking about the possibilities of 16s with low profiles to reduce the oevrall diameter and hence the gearing.

I did contemplate putting 16s on with lower profile tyres to help with gearing but just never got round to doing it, I can't see any issue other than possibly having the car too low & scraping on the ground over bumps etc. you'll just have to calculate the standard rolling radius against the smaller rolling radius that you will be going for and see if you can safely drop the car by that much

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