Tyres and Spacers
Discussion
Hi all,
Haven't been on here for a while as car running well!!!
I need a new set of tyres.
What are the largest I can get away with on the OZ racing wheels? I was thinking bigger tyres, more grip!
Also, I have heard of some people fitting wheel spacers. Do these make the car more stable, or are they just cosmetic?
Haven't been on here for a while as car running well!!!
I need a new set of tyres.
What are the largest I can get away with on the OZ racing wheels? I was thinking bigger tyres, more grip!
Also, I have heard of some people fitting wheel spacers. Do these make the car more stable, or are they just cosmetic?
looking at this chart you could go up to a 225 or even 235 section on a 7" rim 
Spacers may be required if you change to after market wheels with different offset or fit big fat tyres !
Spacers may be required if you change to after market wheels with different offset or fit big fat tyres !
Will fatter tyres actually give you more grip? - the debate starts here!!!!
Larger section tyres with the same aspect ratio will give a larger rolling radius and change the gearing, so the car should accelerate slower (in theory). Lower aspect ratios, to compensate, may have other side effects.
But are these changes detectable in real life?
As I say - this should start a good debate!
Cheers
Tony
Larger section tyres with the same aspect ratio will give a larger rolling radius and change the gearing, so the car should accelerate slower (in theory). Lower aspect ratios, to compensate, may have other side effects.
But are these changes detectable in real life?
As I say - this should start a good debate!
Cheers
Tony
TurboTony said:
But are these changes detectable in real life?
As I say - this should start a good debate!
Cheers
Tony
Well, as you started a debate it'd be rude not to inject my two pence. Once you get to know the charector of a set of tyres you pretty much automatically compensate for the differences in flex. I know that when i drive my car with a higher side wall i can feel the tyre flex when cornering hard, I also know how far it'll flex before it loads the tread and breaks traction, and how much it'll bounce back and then flex the other way... All of that "feedback" is taken into account when lining up for a corner...As I say - this should start a good debate!
Cheers
Tony
On the other hand, my other car has a stupidly low profile tyre on it so no compensation is needed so my line can be a little different - not better, just different.
I prefer taller tyres, I find they suit my driving style more and on the road they are a lot more forgiving (comfortable). Bear in mind your suspension will be set up anticipating a certain amount of shock absorbtion by the tyres, remove/drastically reduce that and you end up with a harsh ride with not a lot of trade off in the handling stakes.
Just my opinion of course...
Keep as close to stock rolling radius as possible or your speedo will be inaccurate and the gearing altered (a bit).
Julesprivate said:
Well, as you started a debate it'd be rude not to inject my two pence. Once you get to know the charector of a set of tyres you pretty much automatically compensate for the differences in flex. I know that when i drive my car with a higher side wall i can feel the tyre flex when cornering hard, I also know how far it'll flex before it loads the tread and breaks traction, and how much it'll bounce back and then flex the other way... All of that "feedback" is taken into account when lining up for a corner...
Blimey !I just thrash mine till I scare myself then slow down a bit
Also bear in mind that the steering will be heavier with fatter tyres. And also: do you want more grip? I've had more fun in the cars I've had with less grip as you know how far you can push. In the grippier cars I'm always loath to push them too much in case they suddenly bite back...
Design said:
Could I run 225/55/15 front and rear?
Yes and when my front tyres wear out I will be doing exactly that, when I was running 60 profile they did rub a bit but only on full lock. To be honest I really don't think that you will notice any difference to traction but they do look very cool . I should point out I am running banded steel wheels , please don't ask me the offset I have no idea !The contact area is proportional to the amount of grip you have and the contact area is entirely dependant on the pressure of the tyre not the shape and that is determined by the weight of the car.
That's all overly simplified but pretty much holds true. All you end up doing is changing the shape of the contact patch which changes how the car reacts to steering input and road surface changes. As Jules said you also get a difference in handling due to the difference in height of the sidewall.
Changing the wheel size can give you more grip but only because it is matched closely with the rest of the suspension to keep the wheel on the ground and give the handling characteristics that allow the car to be driven fast. In other words you need to know what you're doing and I think it is a little bit of a black art.
I can recomend a book called " How to make your car handle" by Fred Puhn if you really want to get geeky about handling.
That's all overly simplified but pretty much holds true. All you end up doing is changing the shape of the contact patch which changes how the car reacts to steering input and road surface changes. As Jules said you also get a difference in handling due to the difference in height of the sidewall.
Changing the wheel size can give you more grip but only because it is matched closely with the rest of the suspension to keep the wheel on the ground and give the handling characteristics that allow the car to be driven fast. In other words you need to know what you're doing and I think it is a little bit of a black art.
I can recomend a book called " How to make your car handle" by Fred Puhn if you really want to get geeky about handling.
Edited by orange_dodo on Wednesday 8th August 21:09
phillpot said:
Blimey !
I just thrash mine till I scare myself then slow down a bit
LOL - I'm sure you'll find if you analysed how you drove you're already doing all of that compensation without realising it... That's how you manage to stay on the road/track LOL.I just thrash mine till I scare myself then slow down a bit
I tend to over analyse stuff internally LOL
orange_dodo said:
The contact area is proportional to the amount of grip you have and the contact area is entirely dependant on the pressure of the tyre not the shape and that is determined by the weight of the car.
That's all overly simplified but pretty much holds true. All you end up doing is changing the shape of the contact patch which changes how the car reacts to steering input and road surface changes. As Jules said you also get a difference in handling due to the difference in height of the sidewall.
Changing the wheel size can give you more grip but only because it is matched closely with the rest of the suspension to keep the wheel on the ground and give the handling characteristics that allow the car to be driven fast. In other words you need to know what you'er doing and I think it is a little bit of a black art.
I can recomend a book called " How to make your car handle" by Fred Puhn if you really want to get geeky about handling.
Are you an engineer by chance That's all overly simplified but pretty much holds true. All you end up doing is changing the shape of the contact patch which changes how the car reacts to steering input and road surface changes. As Jules said you also get a difference in handling due to the difference in height of the sidewall.
Changing the wheel size can give you more grip but only because it is matched closely with the rest of the suspension to keep the wheel on the ground and give the handling characteristics that allow the car to be driven fast. In other words you need to know what you'er doing and I think it is a little bit of a black art.
I can recomend a book called " How to make your car handle" by Fred Puhn if you really want to get geeky about handling.
phillpot said:
Blimey !
I just thrash mine till I scare myself then slow down a bit
Thats about as "technical" as i get too Mike, but i struggle with the slowing down bit and just carry on scaring myself (and other road users too probably)I just thrash mine till I scare myself then slow down a bit
interesting.. Imho 225 is a little wide for a 7" rim.. It will roll more than a 205 which something I personally don't care for. I ran 225 on the rear of the cosworth for a while and they felt 'better with more grip' in my mind the more tread on the road the more grip. That said the 225 tyres were also an improved compound. Anyway I stuck with 205 on the front and 225 rear.
cheers Damian S3
cheers Damian S3
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