jfolley

iTrader: (1)

sorry about posting another one of these threads. I did a bunch of searching, and I spoke with Damian. I could use a little help with wheel sizes and offsets.

I will be using the pettit rear flares and the burnout fronts. I want to run a 12.5" rear wheel and a 10" front. The car has stock struts with ebiach springs. what offsets will work with this set up?

thanks, and sorry,
-John

dclin

iTrader: (4)

https://www.rx7club.com/showpost.php...6&postcount=12

Using these offsets as a reference, then a 18x12.5 would call for a +31ish offset.

This is a conservative fitment, almost near flush. If you want a more aggressive fitment (stretched tires), go with a numerically lower offset.

I have Burnout fenders now with 18x10.5 +43 up front. With 10mm spacers, it takes it to 18x10.3 +33, and is also near flush, with 285/30/18. The equivalent offset for 18x10 would be +27 to maintain the same front spacing.

jfolley

iTrader: (1)

thanks a lot! my next question is will there be an issue with rubbing on the stock strut mounts? Damian mentioned to me that this may be an issue with larger wheels.

dclin

iTrader: (4)

In the front, no, not with a 18x10 +27ish.

The rears, its not so much the shock/springs (since the rear spring perch sits just at or slightly about the diameter of the tire. You're more likely to come into contact with the trailing arm, before the shock/springs.

The 18x12.5 +31ish is going to be really, really close, if not just touching the stock trailing arm. With 18x10.5 +43 in the rear, I had approx 1/2 to 3/4" clearance to the stock trailing arm.

Assuming a 18x12.5" +43 first (I find it easier to change only one variable at a time, when determining fit for different widths and offsets. In this case, I'm changing widths first, offset second), you will need to add 1" on both the front and back spacing. Essentially, you lose the 1/2-3/4" clearance(and then some). 18x12.5 +43 will definitely hit the trailing arm.

Now, factoring the offset of +31(ish), you can take away 12mm (almost 1/2") off the back spacing and add it to the front spacing. It's going to be very, very close.

You can add an aftermarket trailing arm, but don't really know how much clearance it's going to give you. Maybe just enough. You can also take away abit of offset too. There is at least another 1/4" (6mm-ish) before the wheel is COMPLETELY flush with outer fender lip.

https://www.rx7club.com/interior-exterior-audio-26/got-my-pettit-rear-flares-today-123776/

Other factors, such as adding a bit of neg camber (if it doesn't upset handling) can be considered too.

Hope that helps.