thoughts about track rims and tyres

[shimmy]

yep, understand, i have been working on rubber sizes as the michelin specs for Cups.

http://www.tirerack.com/tires/Spec.jsp?make=Michelin&model=Pilot+Sport+Cup

i am trying to tuck the new rubber as close to the strutt as the current one is, assuming that this is as close as you want to get. CSL fronts are et45 and with the 18x10 and 265 cup this means for the inside of the tyre to be in the same place you need an et32

this just leaves the question, what camber is needed to tuck the 265 under the arches if it is sticking out 14.2mm further?

[_Nathan_]

Remember that the width of the tyre face doesn't change and it is the tyre that needs to clear the arch, not the face of the wheel. I'd have liked a lower offset but they couldn't make them any lower, we'll see

Found this useful: http://www.1010tires.com/WheelOffsetCalculator.asp

This car is running 18x10 ET11 all round:

[shimmy]

Nick bell ran 18x10 BBS and later OZ on his car to great effect, worth having a chat with him?

I've got some 18x10 team dynamic 1.3s waiting to go on, fingers crossed my offset calculations were right

ive done my own calcs and your offsets are well out mate :thumbs:


but then i realised you will be running big camber and also want to widen your track as much as possible

from a road car point of view my calcs show that if i want matching rims front and back and 265 tyres (18 or 19) then to maximise the space available inside the front wheel you need to increase the offset on the bigger rims to best size et32 to fit the front as efficiently as possible.

This means the same rims on the rears have a say 5mm bigger to make use of the space to the strutts.

this means that the tyres will be 14.2mm further out, that makes the perfect rim the 18x10 et 30 from the catalogue but i would prefer a 19x10 et32 and hope that the extra camber needed to tuck under the front arch is not too much (-3 hopefully)

obviously different fro you race car, different priorities :supz:

[_Nathan_]

9" is the narrowest rim that a 265 cup can be used on, same with a 250 slick, both suggest 9-10.5 inch wheel. A 250/640/18 Dunlip slick is 10.1" wide, it is designed for a 9.5" wheel. I've had good discussions with the tyre and wheel people about the issue of the car falling over itself as the tyre tucks under and the consensus was to go to a wider wheel to stretch the sidewalls and reduce the wheel moving inside the tyre hence my suggestion of a 10" wheel. My car is heavier than the cup cars so horses for courses and not suggesting what you've found isn't right, just different to what I've seen on my car.

Nick bell ran 18x10 BBS and later OZ on his car to great effect, worth having a chat with him?

I've got some 18x10 team dynamic 1.3s waiting to go on, fingers crossed my offset calculations were right

[shimmy]

Is there a price difference between 18" or 19" Cups? Not that I'm a tight arse git or anything

I will check with the Cups but I've heard difference is negligible as the 18 tyre is actually more rubber than 19 due to profile.

You will get rims alot cheaper but resale I guess will be harder.

The main reason in my mind for 18 rims is the weight saving and handling but if I could get 19 inch Pro Race 1.2 I would probably go for them so my tyre stock is not all redundant'

[Thorney]

6 cars running on 250 wide slicks on the Pro Race 1.2's for a season and never had any issues and tyre wear was enough for John to pikey out all season barely on one set. 265 rear tyre shouldnt be an issue on a 9" rim either but does depend on which one. Dunlop Direza's are fine.

Wheels are about £600 for a set, think we have a few in stock. Rays are better bet of course, I used to run 9" front and 10" rear but at £2500 a set they aren't cheap although even lighter than the Pro Race.

[Hazy]

18" Pro Race 1.2 rims, 18 x 9. Dunlop Direza tyres.

Wheels are cheap and bullet proof, tyres last longer than R888's

Done

thinking about buying another set for our E46 John, how much a set??

Funnily enough I have decided to run with 19" cups only so Hazy is after my 18" with the dunlops on (they are a great tyre and road legal!)

never mind after them, I deffo want them, just been busy!!!! Gotta pick up my new daily $hitter from near you next weekend, so will probably get them then mate :thumbs:

[shane@mbtech]

that is the conclusion i am coming to

what rims, pro race 1.2 18x9 ?

Yes pro race 1.2 18 x 9

It does feel different on the 18s, but ive not been on track with the 19's so cannot pass fair comparison really

Is there a price difference between 18" or 19" Cups? Not that I'm a tight arse git or anything

Negligable tbh wheels,

[3wheels3]

Is there a price difference between 18" or 19" Cups? Not that I'm a tight arse git or anything

[shimmy]

I ran pro race 1.2 this year with 235 40 18 and 265 35 18 a048,

seemed pretty good tbh, but im trying the 265 35 18 pilot sport cups all round next year..... see how they compare.

that is the conclusion i am coming to

what rims, pro race 1.2 18x9 ?

[shane@mbtech]

Nords

part of my plan is to find a reduced weight wheel like the pro race 1.2 and i am not convinced by the effectivelness of the dunlop tyres (but could be convinced)

So i will def need lighter 19 or 18 inch rims (cheap ones) and then fit either 19 or 18 inch 265/35 tyres (you can get both in Cups.)

I ran pro race 1.2 this year with 235 40 18 and 265 35 18 a048,

seemed pretty good tbh, but im trying the 265 35 18 pilot sport cups all round next year..... see how they compare.

[_Nathan_]

Bitch.

[shimmy]

PS. Remortgage and get 18x10 BBS E88 all round and I may want to marry you.

not sure id have you :smokin:

[_Nathan_]

265 is too wide for a 9" wheel really (same for a 250 slick), look at the shape they make on the wheel and how the car looks to falls over the tyre when cornering.



9.5 is IMO the ideal wheel width but 10" are more common (Rays are a good 9.5 option but expensive). Pro Race 1.3 available in 10" and the tyre won't move about so much.

If you are sticking with 19" just stick with the CSL wheel unless you want to spend a fortune on nice BBS or Rays rims.

PS. Remortgage and get 18x10 BBS E88 all round and I may want to marry you.

[glendog74]

my previous rule;


1. No Ring laps without cage

:thumbs:

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