I have a 1990 RX7 GXL which I am currently doing a motor swap and a few mild modifications such as Apex'i intake, Racing Beat header with test pipe and cork sports single cat-back system, Mazdatrix short shifter, and suspension. I will be going with the Racing Beat spring kit which is about an 1.0" of drop. So my problem is this, I want to go with 17x8 up front and 17x9 in the rear, is a +35 offset going to cause rubbing issues? Or should I go higher with like a +42?? Also, is anyone else using Corksport's single cat-back system? It looks like an Apex'i knock-off, any opinions? Good Sound? Will it shoot fire like my Apex'i N1? Lol....anyway, if anyone can help me out with my wheel/tire issue I would greatly appreciate it. Thanks!

 

I will be selling quite a few parts from a 90 and a 91 RX7. I have a few listed now; cat-back exhaust and blue cloth seats. I will have lots more parts for sale very soon, such as taillights, front clips, transmission, and misc. engine and interior parts. Hard to find switches...etc. Just follow this link if you are looking for any parts for your 2nd Gen.

E-AutomotiveSolutions......eBay Auctions

 

I'd reccomend that you use 8" wide wheels all around and ditch the stagger. Staggered wheels and tires will cause the car to understeer like a pig, it'll cost more for wheels and tires, you'll loose the ability to rotate tires, it'll cause slower acceleration due to increased inertia and it's just not needed with an NA. I've got some minor engine mods on my S5 NA and with some decent summer tires I can't get the wheels to spin unless I drop the clutch from high RPM's. Wide tires aren't needed, all they do is hurt your performance.

For the offset, look at the official wheel fitment thread and do a search.

42 is way too much offset, the wheels will run into the springs and you won't even be able to get them on properly, nevermind drive on them (higher offset = further in). You'll want something in the order of 30-35mm in the front with 17x8's in order to clear everything. I've got 17x8's with a 30mm offset all around with 225/45/17's and it fits perfectly, no rubbing ever, even at the track (road course on stock suspension, so plenty of body roll). you probably don't want to go more than the 225/45/17's as many of those who've tried 235's have had rubbing problems, whereas 225's fit just fine, and is the largest safe choice for tire size.

 

Couldn't you just go with a smaller offest in the front to equal out the front and back tires? I mean, how bad can it understeer? My friend has a 2001 Z06 Vette and the difference in tire size from the front to the rear is insane. I understand the Z06 has more power so of course it will have less understeer, but I can't see it being a problem going with staggered sizes, since it isn't going to see the track anytime soon. I just want a nice, SEMI-reliable car to have a little fun in.

 

I have 17 by 8 34 front and 17 by 9 34 offset rears. I am running 225/45/17 in the front, 265/40/17 rears. I plan on switching to 235/40/17 on the front in the future. Oh yes, I am running Ground controls with Koni Yellows.

Usually a rear biased stagger will make a car understeer, but for me until I go to track and see if I need to tune the suspension for oversteer than it's no concern for me right now. The understeer caused from the stagger can be fixed, and you never know, it might suit your driving style.

 

Vettes are designed to have larger rear tires, RX-7's are designed to have equal sized tires front and rear. There's a big difference in them. You can't really compare cars in that way without a lot more knowledge about them, they're too different.

With enough tuning with aftermarket suspensions you could get it to be neutral, but with just about any off the shelf suspension (including yours) it'll understeer like a pig. Mine understeers with equal tires (stock suspension with some braces, poly bushings and RB sways).

Offset has very little effect on handling, so no, you can't get it to "equal out" with the offsets.

 

I have 17x8 +35 with 235 in front with a little fender modding.
17x10 +35 with 275 out back, no fender mods.
I have KSport Coilovers.
Handles great, no problems.

 

On the current suspension you don't have much adjustability.

Keep in mind you can change understeer/oversteer by changing the height of your coilovers, sway bars, and the stiffness on adjustable shocks.

If you're dead set on staggered setup, put the staggered sizes on and see if you notice anything. I bet the first couple of times at the track it won't matter if you feel understeer/oversteer(to a certain extent). Ideally, you would want to learn your car first before doing any modding whatsoever.


The reason I am going with a rear biased staggered setup is because my motor is putting down 350whp, so I need all the rubber I can fit.

 

Thank you Pat! I am not worried about the understeer, cause like i said, I'm not taking it to the track. This is going to be a street car. I just wanted to make sure that a +35 offset would work for me with the wheel/tire package I want. I have also been looking into Atkins Supercharger setups and that could be a real possiblity down the road. So if that happens, I want as much rubber in the rear as possible. Thanks for all your replies! Very helpful!

 

I would drop the offset down to around +30 with the 8.0" up front.
...unless you're trying to gain clearance with certain coilover kits.


-Ted