Kit_Chris

Sure, it's an extreme comparaison. So is GT racing, or any other kind of high level motorsport for that matter. You need not agree, it's alright!

Regards,
Chris

UK952

F1 cars have small wheels beacuse the regs say they have to be that size. The tyres provide a lot of the 'suspension' movement (50%?) and this movement is undamped. Better to limit the tyre movement and use the suspension to do the work with proper damper control.
No doubt there is an optimum point and after that you are just getting bigger for style.
Brakes bigger than they need to be result in greater unsprung weight which is bad.
Tony

Kit_Chris

OK. You are correct about F1 regulation, I forgot that big money and clever engineering can make sub-optimal designs work quite well. My mistake for making the F1 comparaison in the first place, I wrongly assumed engineers retained the small wheel solution because it provided the best performance.

I wouldn't fit 13" wheels on street going Porsche (as F1 cars have), but the 16" Fuchs I drove with race compounds were as stiff and provided as sharp steering response as much larger combos and the car seemed to hook up much better, a characteristic I attribute to the quicker suspension mouvements, with its lighter parts. For all those who've discarded less glamorous looking wheels and stock brakes, give it a good try on a track setting and you'll be amazed. As I was.

Regards,
Chris

UK952

Indeed my track wheels are also 16" partly as the rubber is a lot cheaper. In our cars unless really hardcore the suspension rates are a lot softer so tyre deflection is less of an issue. Another point, IMHO a tyre that produces the ultimate grip (which a lower profile might) may not produce the best laptime as when it lets go it goes so fast you cannot catch it, a slightly higher profile may give more feedback of the approaching limits and more control on the other side of them, resulting in better feel and faster laps.
Tony

ehall

This is no more than a theoretical question, as I'm no hot shoe, but wouldn't the ability to get into a corner more accurately, with lower aspect tires, be better, and faster, than counting on the give of more sidewall, to save your butt when you screw up? ie..the more precisely you get into a turn, the less cahnce you need the extra forgiveness of the 16" side wall? I don't know, thus the question? TIA

UK952

Not an expert either but in my experience tyres with a gentle limit are much easier to get the best out of than ones that bite. In an ideal world where the ideal line at the perfect speed was possible then maximum grip would be tthe way to go. However with constant changes something that doesn't result in you heading for the tyre wall backwards at the slightest error is more likely to get you to the end of the race.
I find that slicks on my 16" wheels allow this there is a definate feeling of getting near the edge. However I haven't tried larger slicks so I cant compare.
I have tried a number of different road tyres on 17's and I found with the grippiest - Bridgestone S02's N-3 on the track when they let go they went Very suddenly and I would end up fscing the wrong way or fishtailing with the Dunlop SP9000 I have now I can hang the tail out and look like a driving God or keep just inside this limit easily. Ultimately they are less grippy but I can get closer to the edge without risking spinning. In a race I think the grippier tyres would end in me spinning off (or driving slower to ensure I didn't) the less grippy telegraph the limits so when I am on an unusal line or braking late I could hold it together and get to the finish.
I cannot think of any formula where the tyres are really low profile. I guess there could be an issue with bending the rims riding the Kurbs etc. or it could be the transistion from grip to slip becomes too sudden.
I also find that the limits on slicks (only limited experience 16" on the 944 and karting) are much better telegraphed than road tyres, this was unexpected as the higher grip levels led me to expect them to be a bit trickier. I guess this is down to the lack of squirming tread blocks.
Tony

951_RS

I messed up my post with saying high profile, when I meant low profile, and then when I think about it I was wrong anyways

UK952

That is the reverse of my experience, whenever I have had a tyre roll onto the sidewall it has produced less grip,
Tony

Duke

I agree with Tony,
when the outside tire rolls it runs on the sidewall - not good for traction.

Personally I like a stiff sidewall with the proper camber settings..

951_RS

Really? I've always felt like because more rubber was in contact with the road it had more grip, maybe you roll it onto the sidewall too quickly

Or! Maybe I'm wrong... I haven't had much experience with high profile tires in fast driving, I've always used low profile

streckfu's

that part of the tire is not designed for grip. The sidewall is for support only.