[Eric SS]

Seriously considering switching to 18" from 19" track wheels for cost reasons. Anyone have any photos of what our cars look like with an 18" setup on it? I'm aware that some grinding of the strut would be needed. with my 5mm spacers and camber plates it won't be much though. Thanks.

[Provoste]

Originally Posted by Eric SS

Seriously considering switching to 18" from 19" track wheels for cost reasons. Anyone have any photos of what our cars look like with an 18" setup on it? I'm aware that some grinding of the strut would be needed. with my 5mm spacers and camber plates it won't be much though. Thanks.

Beast mode. 18x10 ET25 running 285/645 P-zero DH take-offs.

[Eric SS]

Awesome. Thank you! That is beast mode with those tires. Is that equivalent to a 40 series tire if you convert slicks to aspect ratio?

[rotis]

This is 18x11 square, with 315/30-18. The car is lowered nearly an inch, but with the smaller overall diameter the fender gap ends up about the same as stock.

I got one close-up shot, and one at distance. heh

[Eric SS]

Thanks Rotis. If I'm not mistaken you have offset struts right? I'd love to go square 18x11 but I'm sure I'd have to do a ton of grinding even with my 5mm spacers and camber plates

What offset are your wheels?

[rotis]

Yes, offset struts. No way these would fit under the stock SS fenders without gaining more room on the inside.

The wheels are +43, I run a 20mm spacer in front for an effective offset of +23. The picture is at -3.7deg of camber.

[RXtacy]

Originally Posted by Provoste

Beast mode. 18x10 ET25 running 285/645 P-zero DH take-offs.

Where are you getting your takeoffs? How long do they typically last you?

[Provoste]

Originally Posted by Eric SS

Awesome. Thank you! That is beast mode with those tires. Is that equivalent to a 40 series tire if you convert slicks to aspect ratio?

No, acctually somewhere between a 30-35 series sidewall.... closer to 285/30!

OD for 285/645 18: 25.2

OD for 285/40 18: 27.0
OD for 285/35 18: 26.1
OD for 285/30 18: 24.9

[Provoste]

Originally Posted by RXtacy

Where are you getting your takeoffs? How long do they typically last you?

John Berget Racing Tire. The P-Zero's are fantastic, on the last set- I ran 3 days at Putnam Park, and 2 days at Mid Ohio. Probably 18-20 HC's in all. They never completely gave up, though the last few sessions @ mid ohio, they had lost their best for sure. $120 per tire. I have a fresh set for VIR next month!

[RXtacy]

Originally Posted by Provoste

John Berget Racing Tire. The P-Zero's are fantastic, on the last set- I ran 3 days at Putnam Park, and 2 days at Mid Ohio. Probably 18-20 HC's in all. They never completely gave up, though the last few sessions @ mid ohio, they had lost their best for sure. $120 per tire. I have a fresh set for VIR next month!

Wow that's better life than I was expecting, and definitely hard to argue with the price!

[Magsz]

For the layman...

What is the benefit of a smaller rim/tire combination besides cost?

[RXtacy]

Originally Posted by Magsz

For the layman...

What is the benefit of a smaller rim/tire combination besides cost?

Lower unsprung weight = quicker acceleration
Smaller diameter (better effective gear ratio) = quicker acceleration

[Provoste]

Originally Posted by RXtacy

Lower unsprung weight = quicker acceleration
Smaller diameter (better effective gear ratio) = quicker acceleration

Exactly. All VERY good things, and when combined... makes a very noticeable difference on track.

FYI, the 285/645 18 is a 7.35% smaller rear OD than stock. That’s a BIG difference in gearing which rocks on track!

[Norm Peterson]

Originally Posted by Magsz

For the layman...

What is the benefit of a smaller rim/tire combination besides cost?

You also lower both the sprung mass CG height and the geometric roll centers - without affecting things like suspension geometry and half-shaft angularity at all.


Norm