Rim/tire size choice for track

[Chalkie]

Chalkie, what suspension have you got ? Any pics with the fenders/wheels ?

AST RACE DAMPERS
KW CAMBER ADJUSTABLE TOP MOUNTS

[fuscobal]

Made some comparison calculations between the 2 wheels I have for track :

1) OEM Denvers 7.5x17'' ; ET51 ; Kumho V70a on 225/45/17 (224 effective width)
2) TD 1.2 PRO Race 8x18'' ; ET45 ; Toyo R888 on 235/40/18 (244 effective width)

OEM > 7.5'' = 191mm
Tire = 224mm
Tire goes out of the rim on each side (224-191)/2 = 16.5mm
ET51 means :
1) the distance from the rim mounting point to the outer tire extremity would be 224/2 - 51 = 61mm
2) the distance from the rim mounting point to the inner tire extremity would be 224/2 + 51 = 163mm

Aftermarket > 8'' = 203mm
Tire = 244mm
Tire goes out of the rim on each side (244-203)/2 = 20.5mm
ET45 means :
1) the distance from the rim mounting point to the outer tire extremity would be 244/2 - 45 = 77mm
2) the distance from the rim mounting point to the inner tire extremity would be 244/2 + 45 = 167mm

By comparison :

1) The aftermarket tire will stick out 77-61 = 16mm more than OEM (this is bad for those that have clearance issues)
2) The aftermarket tire will be closer to the strut by 167-163 = 4mm (this is also bad for those who have strut clearance issues)

[rex]

Looks like you might need some Kerscher or Seibon fenders!

[fuscobal]

Only way to know it is when I'll install the new wheels at the end of september...hopefully not !

[Chalkie]

here is the car running load on 255 35 18 toyo 888's she's currently on 255 35 18 Yokos AD08's both give no problems with rubbing either loaded or on full lock...

[fuscobal]

Can't understand how is that possible with OEM fenders. What do you mean by rolled slightly ? (5mm, 1cm ?). Chalkie, please also specify what ET have you got to those 8.5 x 18 rims ?

PS : Maybe those AST's are much stiffer than our B16s !

[danishmkvgti]

Can't understand how is that possible with OEM fenders. What do you mean by rolled slightly ? (5mm, 1cm ?). Chalkie, please also specify what ET have you got to those 8.5 x 18 rims ?

PS : Maybe those AST's are much stiffer than our B16s !

Linear springs maybe? 

[Chalkie]

et50 8.5x18

they use a special machine to roll the arches ask your local bodyshop...

[rex]

And guys, I also think the circuit is important.
I have no rubbing at Hungaroring with a 2cm lower suspension and ET40 rims. But I have rubbing at Nordschleife with 2cm higher suspension and ET50 rims.
So my guess is that there is rubbing on that Golf on Nordschleife. It just depends where you are going.
I will search for a setup that is ok for all tracks because rubbing is annoying and also dangerous.

[Chalkie]

no rubbing at Nordschliefe either

[rex]

Well guys, it just makes no sense to me...
We have the TT arms that take the wheel out by another 1cm, but still it makes no sense.

*Edit laurent had something similar to the TT arms, 8x18 ET 45 OZ wheels and had rubbing on the Nordschleife. I just don't understand why we have so different results...

[fuscobal]

rex, It's also weird the 255 tire doesn't touch the damper on the inside. For me, with 235 the tire sits about 10mm away from the Bilstein damper and I have ET46. 255 should touch it with ET50 !!!

[rex]

 . Nice... So, this is clearly out of my league. O have no idea what to believe!

[the bruce]

+1

many of the boys in the US run 245 or even 255

Are the US model fenders so different or don't they care about rubbing? 

[Chalkie]

oh yeah i have the tt arms too...