Performance tyre sizes

[simonsparrow]

I've noticed that some of the people who sprint Cerberas still use "16 wheels and tyres.

I'm interested if this is a deliberate choice, or more a case of regulations, or using what you already have.

I know the "18 wheels look great, but I remember a post last year by GreenV8S which basically said that low profile tyres such as the "18 inch sizes may offer more grip, but will tend to give way more suddenly than slightly less grippy, but more forgiving 'higher' profile tyres.

As a slower witted driver who does track days and drives on country roads, I thought I'd keep going with the "16 wheels for a while on this basis.

Anyone else resisited the lure of bling-bling wheels? (I know I'm weakening.... )

[S-X-S]

You're halfway there with that assumption.

Grip is a formula derived by factors such as contact patch and weight distribution, but drag can can also harm grip, and you can get tyre drag very easily if you're running low on PSI.

16's are ideal for circuit racing, many seem to think this, you have a lot more fun and time to correct back twitching moments.

Low profiles give you a misleading sensation of being able to take the corner flat on, and even the most veteran of drivers get caught out and spin out or worse

I'd recommend having a set of 16's with road-legal slicks to take out on your track days, and change back to your lurvly spiders for everyday road presence.

[simonsparrow]

Guess I was assuming that the "18 tyres have more grip as the contact patch is bigger (as the tyres are wider and slightly greater diameter).

Your suggestion sounds like a good one ;-)

[andy4200]

I've avoided the bling of 18's but I've just last week put on a set of 17's as I prefer the look.
I kept my 16's with a set of barely legal Toyo's on as frankly they would only be worth about 100 quid but will be useful as a spare set for emergencies or track days.

[S-X-S]

simonsparrow said:

Guess I was assuming that the "18 tyres have more grip as the contact patch is bigger (as the tyres are wider and slightly greater diameter). Your suggestion sounds like a good one ;-)

If you like at GT cars, they are running some real fat tyres, and when you put in the formula of sidewall ratio, the widewall actually is very fat.

Ie. 345/30 is a much bigger sidewall than 255/40.

I guess the best way to look at things from a racing perspective would be to look at the agility and control in an F1 car, and look at the tiny wheels and faaaat tyres....

Plus dont forget, for different tracks you will start to get an idea for how much psi you wanna keep in them and what brake bias to set-up etc., the pro's go all out and set their car up differently for every track also atmospheric conditions have an impact on configuration settings too.
For us wannabes, a lot of us think the safest bet is a nice medium profile strong tyre with small light alloys so that the brakes dont have to work overtime and kill your discs etc.... is a great and budget concious route, you will be amazed at how much play you have with wider/softer tyres.... just make sure to change the driving style when you wack the bling 18's back on...


Peter (GreenV8S) can give more info on all of this, as he is an avid sprinter and techie in race-car setups, and after he's trained me up in mine, I'll be joining in the fun too albeit a little easy on the throttle (dont forget your promise peter!)