Ok, I searched the archives first but found so many different offsets that I don't know which one is correct.

I have an 88 Formula. I know the bolt patter is 5-100mm just need to know the proper offset for the front and rear so I can buy my new wheels.

Any help would be greatly appreciated. Sorry, no reward, I am fresh out of cash.

------------------
AIM - SWags2933

84 Fiero SE (being modified)
88 Formula

The offset of the new wheels depends on what size wheels you are buying, as wider wheels will require different offsets to look right.

What size wheels are you wanting to get? Give more info and help ye shall receive Lots of guys know what's up here with wheels, helped me out a lot.

Bryce
88 GT

With a 17" wheel you would be safe with a 40mm to 42mm offset.......

------------------

Classic Fiero Owners Group International

To answer your question fromt is 37mm and rear 41mm.
On which offset is good for 17" you will get one different answer per person. I have seen as high as 45mm. Most afttermarket go from 35mm to 45mm.

------------------
Alex4mula
:) Red-Original Owner & White-1/94 with PM (:

Rear offset on the '88's is actually 35mm. The "ideal" offset for the front for a 7" wide rim is 48mm, but you will have a tought time finding that in a 5x100 without spending big$$ The more common 40-45 range will work, but will stick out a bit at the front. I'm looking for a staggered size set with 17x7 front and 17x8 or 17x9 rear.

The wheel diameter (17") doesn't matter at all with the offset, it's the wheel width that matters. On my 88, I just got 7" fronts with 40mm offset and 8" rears with 40mm offset. I am very pleased with how they look, and they don't stick out any noticable amount. If you figure it all through, there's only about 10mm of change in the offset, which really is hard to notice. Here's a pic of the car from a slight angle, just so you can see how well everything lines up. By the way, I have 215/45/17 and 245/40/17 tires.

Bryce
88 GT

Rear offset on 88s IS 41mm not 35mm. 15"x7" on 86-87 is the one with 35mm. These are the codes;

· XBZ: 86-87 (35mm offset)
· XRS, XXJ: back of 88 (41mm offset)

Actually, it truns out the site that provided that info was wrong. There was a correction posted to one of the Fiero mailing lists a while back. The offsets for the 15x7 wheels are the same.

quote Originally posted by Wannabe: Actually, it truns out the site that provided that info was wrong. There was a correction posted to one of the Fiero mailing lists a while back. The offsets for the 15x7 wheels are the same.

I second this. I had a set of 86 GT wheels that were *identical* to my 88 Formula's rear wheels. Same casting.

------------------
Raydar

From the Department of Redundancy Department.

Oh well... Nobody is perfect
Will that mean that the 18x8.5 35mm offset Konig Imagine should fit fine in my car??

------------------
Alex4mula
:) Red-Original Owner & White-1/94 with PM (:

Alex, I would think that an 8.5 inch wheel with only 35 mm offset would be a little funky looking. If you do the math, you'll find that on the front that wheel will stick out about 1.4" further. If you want an 18x8.5, an ideal offset would be 60-70mm to retain the same "stick out" amount as stock. You could get away with a 50, but only 35 would probably make your tires stick out past the edge of your fender lip.

Bryce
88 GT

Ok, thanks for the information.

What I am understanding is that if I want a 17"x7" wheel in the front I should look at about a 40mm offset and if I want a 17"x9" wheel out back then I should look at about a 50-60mm offset.

Would this be somewhat accurate? Won't the larger offset put the wheel closer to my springs and cause rubbing?

By the way I am look at getting the Konig Toxxins for the car. I have seen them on a couple of Fiero's and they look pretty sweet.

------------------
AIM - SWags2933

84 Fiero SE (being modified)
88 Formula

The 18x8.5 is for the back. These offsets always confuse me. What does a higher offset number does, phush the wheel out of fender or in? Tks.

------------------
Alex4mula
:) Red-Original Owner & White-1/94 with PM (:

IwannaIRM - Yeah, that's about right. There are "ideal" setups that would be more specific, but the affordable wheels use the offsets you gave there, and are easier to obtain. You are right, the larger offset and wider wheel both push your wheel in closer to the suspension. On fronts, you'll have tons of room. On the rears, with a 9" wheel and stock, you'd be pushing it with a 50mm offset. I know you could clearance the suspension a little where the strut bolts to the spindle and have the room you needed with a 40, but I'm not sure about 50, somebody else that's done it will have to verify that.

Alex4mula - Read up buddy: http://www.usacomp.com/Offset.htm

With an 18x8.5 in the back, you would still want about a 60mm offset. With 18s, you should clear the suspension fine (assuming you use tires that hug the wheels real tightly).

Again, I'm not an authority on this at all, just trying to help out with ideas. 1FST2M6, Artherd, and TRiAD all seem to have lots of good info on wheels. 1FST2M6 already has monster wheels on his car (with earlier suspension, I believe).

Bryce
88 GT

Keeping the same offset keeps the mounting face of the wheel the same distance from the centerline, meaning, if you put on a wheel with same offset, but 1.5" wider, it will stick out .75" more, while the inside edge will be .75" closer to the frame/strut/whatever.

Correct...

The decision for offset lies in re-locating the wider wheels slightly 'inboard' so that their OUTTER surface does not CONTACT THE BODY of the car

This means the wheels are going to stick IN towards the car more, closer to the strut/etc.

Practically this must mean we push the wheels in somewhat, if we are going to a larger size.

Knuckle interfearance with 17" and larger wheels (on 88 cars, I only know 88s, keep this in mind!) is non-existant, as there is no metal untill we are well up towards the spring itself.

Some have fit 17x9" rear wheels (and I belive 265/40/17) tyres under *STOCK* 88 rear springs... I have 18x10" (65mm offset) with 265/35/18 on order

This will certinly require a coilover suspension, but more importantly, I belive I may be one of the first to actually clearance such a large wheel into the back of a Fiero.

It's uncharted territory, and the real proof will be "does it ever contact anywhere?" after I put everything all together

Best!
Ben.

quote Originally posted by Wannabe: Keeping the same offset keeps the mounting face of the wheel the same distance from the centerline,meaning, if you put on a wheel with same offset, but 1.5" wider, it will stick out .75" more, while the inside edge will be .75" closer to the frame/strut/whatever.

------------------

Ben Cannon
88 Formula, T-top, Metalic Red           "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver                     -Mel Gibson, "Braveheart"

Well.. according to the explanation at http://www.usacomp.com/Offset.htm a positive offset of 65mm will push the wheel outward 1.2" (bolt face 1.2" closer to inner edge). Or maybe they have the signs incorrect....

Compomotive is the only people I've ever heard use this particular definition. They have it backward from most everybody else.
I've always heard offset defined as the distance between the hub flange and the centerline of the wheel. A more positive offset will move the hub face towards the front (outside) of the wheel, therefore moving the wheel in.
Backspacing is usually defined as the distance between the rear edge of the wheel and the back of the hub flange.

------------------
Raydar

From the Department of Redundancy Department.

Alright...my interpretation of installing 18x8.5 on the rears.

You start with a 7" wheel at 35mm offset. The 8.5" wheel adds about 38mm of additional wheel thickness.

If you were to keep the stock offset (35mm) with the new wheel, that would add .75" (19mm) of thickness to both sides of the wheel. This would make the wheel stick out .75"(19mm) further on the outside, and .75"(19mm) further in on the inside.

If you increase the wheel offset to 65mm, that will effectively add 30mm of the added offset to the inside of the wheel (suck it in the wheelwell). If you do this, you end up with 30mm of your *added* wheel thickness to the inside of the wheel, and only 8mm to the outside of the wheel. SOOO, this require 30mm additional clearance on the inside (factoring in 18" sizes) and 8mm additional clearance on the outside.

8mm of added outer wheel will hardly be noticable, and with such a big wheel, it would give it that "flush with the body" look, in my opinion. The added 30mm (1.2") on the inside of the wheel, you should be fine on the 88 rear suspension; again, this is assuming you are getting a low profile tire that won't rub on the bottom of the spring perch on the strut housing. I'd imagine you'd want to go with something like a 35 series, effectively keeping the tire size close to stock as well.

This making sense?

Bryce
88 GT

Now I get it. Anyway, I agree that .75" towards the outside may not look too good. With a 45mm ofset it would be about .35". That maybe could be ok but not sure. Thanks all for the clarification.