18x8.5 Offset 46 w/225x40

18x10 Offset 54 w/265x35

Do I need any spacers?

Please let me know.

TIA

 

I think that front offset is WAY off and won't fit...but someone with more knowledge than me will pipe up in a minute. I think you generally want a number greater than 50 for the front offset, especially on a wheel that wide.

 

Front ET needs to be around 56mm or more, 60+ would be ideal. Spacer would only make it worse.

 

this might help.

 

This is how the front 8" and 47mm looks like; https://rennlist.com/forums/928-foru...18-wheels.html

 

8.5" will stick out 6mm more plus 1mm for ET difference. Not good.

 

Not good at all!

 

What is the optimum 18 Offset? Along with, optimum front and rear wheel width?

 

Well, all parts go together... you need the right width with the right offset so there is probably NO PERFECT answer.

I would say an 8.5" wheel up front running a 255 or 265 (not sure which comes in 18") would be a GREAT tire size for the front of a 928. IF the wheel is 8.5" then you need the offset that Erkka mentioned at the beginning... about 62mm would probably work great. It would not stick out and damage the fenders anyway. The only question would be if there is enough room on the back side.

You might also call David Roberts at 928 Specialists. IMHO NO ONE is better with wheel fitments on 928's than he is! He has seen it and tried it all I think and has some BEAUTIFUL cars to show for it too!

 

Will do, thanks.

 

It has very little to do with wheel diameter and all to do with how wide wheel is.

How wide tires you want to use? Larger the wheel diameter smaller window there is for wheel/tire width relationship. This will determine what combinations are ok.

 

Not really but its fairly easy to limit rack movement by installing second stop to rack ends. Still, 265 is pushing it.

 

Good question. I think I want 18 Turbo Twists.

 

Erkka,

I don't think 265 is out there... Aren't there some guys running 285's w/o any mods up front???? I think with MK's fender flares (and they were not huge) he was running 305's or something like that!

 

They must either have rack movement limited or simply not care about full lock rubbing. With exactly right ET 8.5" wheel and 265 will probably work but it also depends on real tire width. 265 can be 255 or even less in reality. Also of the charts caster alignment will buy some room on fender top and racers tend to use as much caster as possible.