15's and performance increase over 17s..??

[EVOgone]

How does this work....its the RR/weight that counts. Tyres are nearly the same weight as the tyres so why does it mater if you have 205/50 on 15 or 205/40 on 17 if the combined weight is the same and the RR is the same then how do you get this extra performance...??

15" dynamic wheel and 205/50 tyre RR=293 W=18kg approx

vs

16" std 182 wheel and 205/45 PE2 RR=295 W=20kg approx

vs

17" supperlegra / turini and 205/40 tyres RR=298 W=16kg approx

15" supperlegra / turini and 205/50 tyres RR=283 W=15kg approx

If the RR are nearly the same and the weight is less than the std car then wheres this big performance decrease with going 17's (with the light wheels)..?

After trying 15s this week i think its all in the head....

Advantages of 15 are that you can get track tyres cheeper i agree.

 

[Fred@BTM]

with my lightweight 17's there's virtually no difference (the wheels are lighter than the tyres in my case!!)

 

[V1NNY]

mine too, strange that the pilot sports weigh a lot for some reason, the toyo proxes weigh nothing really

 

[EVOgone]

mine too, strange that the pilot sports weigh a lot for some reason, the toyo proxes weigh nothing really

Its the 182 wheel that weighs a ton..!

 

[Fred@BTM]

anywheel is heavy compared to a superL

 

[V1NNY]

not the Toyo's lol, they weigh nothing at all, can see why they are a budget tyre

 

[Martin_172]

i was told it was the Rolling Radius that kills the smaller engines, not sure about the bigger ones.

 

[V1NNY]

get a lower profile tyre then

 

[EVOgone]

i was told it was the Rolling Radius that kills the smaller engines, not sure about the bigger ones.

True but all of the above are basically the same RR just the weights are different...

 

[Fred@BTM]

weight makes a massive difference

 

[V1NNY]

with the leggeras the steering feels lighter too

 

[tim_foster23]

with lower profile tyres u risk curbin ya rims easier and it takes out some of the steering performance so ive bin told

 

[Gary G]

Its the 182 wheel that weighs a ton..!

9.7kg's by my scales lol. IIRC some have weighed them in at over 10kg's!!!

 

[EVOgone]

with lower profile tyres u risk curbin ya rims easier and it takes out some of the steering performance so ive bin told

If you curb them thats your own fault, doesnt matter if they are 18's or 15's. Its the tyre overhang that helps this not the wheel size. If anything you will get more steering response on a lower profile...

 

[V1NNY]

but the ride wuality is comprimised on a lower profile tyre

 

[Neil G]

But more road 'feel' and tramlining

better steering though due to reduced sidewall flex

 

[EVOgone]

but the ride wuality is comprimised on a lower profile tyre

The thread is about performance not comfort though..... Do see high performance cars with 50 profile tyres...

 

[Fred@BTM]

with lower profile tyres u risk curbin ya rims easier and it takes out some of the steering performance so ive bin told

mine feels much more direct with the skinny tyres, with 15's and road tyres its a bit "spongy", 15's and slicks is awesome though!

 

[almaghrbi]

I tried loads of tyre sizes and rims on the track and my conclusion is 16' are the fastest rim and 215/40/16 is the best you can have. The reason is the following

If you go 15' they are lighter but you end up having to go for 215/45 to compromise for the size and that means faster straight line speed (acceleration) but the side wall of the tyre is now higher it is now 45% * 215mm rather 40% * 215mm Hence lower lap times on the track

If you go 17' you can not find the tyre that fits other than 205/45 hence less straight line speed and less of a grip on the corner as well.

After thrashing renault at the beginging and after lots of testing, I realized they were not aweful after all. The suggested 16' was the best option.

Now if you say why the racer is running slicks on 15' then the answer is, they had to compromise, not a lot of good slicks availble in 16'

Confusing! I say so,

 

[Fred@BTM]

If you go 15' they are lighter but you end up having to go for 215/45 to compromise for the size and that means faster straight line speed (acceleration) but the side wall of the tyre is now higher it is now 45% * 215mm rather 40% * 215mm Hence lower lap times on the track

we were running 205/50 15's which worked quite well, too much flex in the tyre though

the 15michelins slicks the cup racers use have been the best i've tried, closley followed by the kumo's, pilot sport cups next for me

 

[y0z2a]

michelin only make that 15" slick for the cup race series... nothing else, so why didn't they make it in a 16"

?

ride height is my guess. Lower CoG

/y0z

 

[almaghrbi]

michelin only make that 15" slick for the cup race series... nothing else, so why didn't they make it in a 16"

?

ride height is my guess. Lower CoG

/y0z

Not really its 15' on 50, which will be similar to 16' on 40 they are still compromising on higher sidewall in my opinion

 

[Fred@BTM]

its not a 50 profile though?? Yoz what the size of the slicks again??

19/57 15 IIRC??

 

[EVOgone]

michelin only make that 15" slick for the cup race series... nothing else, so why didn't they make it in a 16"

?

ride height is my guess. Lower CoG

/y0z

Not true.. Michelin do slicks in 16" for the Group N cars. Fit straight onto Turinis. RR is great than the rest as their 20x61 16's but the tyre flex is minimal.

http://www.renault-sport.com/en/rallye/clio_groupe_n/technique.php

Personally i think 17" turinis/supperleggs and 205/40 17 Toyo R888 would be the best combination.

 

[thedoc]

Isn't it all to do with inertia and momentum.. the further the maximum weight of the wheel (rim) is from the centre, the more work required to turn the wheel.. or something like that..

 

[EVOgone]

Isn't it all to do with inertia and momentum.. the further the maximum weight of the wheel (rim) is from the centre, the more work required to turn the wheel.. or something like that..

You are quite correct but its marginal to say the least. In the examples above the 172 option described is lighter than standard...

 

[Akira2506]

Team Dynamics Pro Race 2s (5.5kg) with 195/45/15 rubber.

I haven't tried that many, and I've never been on track...so im no pr0, but...

- I like the 15" rim for mass, radius and ride-height reasons. Also cheaper rubber. Only neg is it doesnt fill the arch...
- I like the 195 width because it stops tramlining and again...cost
- I like the 45% profile, I dont think you loose that much ride quality. If you're already sitting on stiffened suspension, then ur hardly in it for the comfort. 45 profile gives better ride height, less flexing, more road feel...but... this time the negative is cost.

I guess it's down to personal prefference and what you're doing with ur car.

However, fact is fact... and the fact is white wheels pwn.



-Akira

 

[V1NNY]

Still like my 17's as they are massive lol

 

[MAXIBOY]

still like 18,s on 35 profiles

 

[V1NNY]

lol, Gareth had 19's on his lol

 

[Phill1978]

jim had 21`s on his lol

 

[y0z2a]

Not true.. Michelin do slicks in 16" for the Group N cars. Fit straight onto Turinis. RR is great than the rest as their 20x61 16's but the tyre flex is minimal.

http://www.renault-sport.com/en/rallye/clio_groupe_n/technique.php

Personally i think 17" turinis/supperleggs and 205/40 17 Toyo R888 would be the best combination.

Yes, but the S9B (IIRC) is only made for the Clio Championship.

Same as the Pilot Sport Cup on the 15" was only made for the Porsche Cup for the older cars... (According the guys who do the tyres at theese races - they may be wrong, and are only going by what they are told...)

/y0z