I've looked, I've searched, now I'm just more confused.

I hate typing up "will they fit" threads, but I need second opinions before I'm stuck with circular shaped door stops. Here’s what I’ve got so far:

The combo in question:
The rim 18x8, 35+ offset, 74mm Centerbore.
The tires on them are 235/40/r18. If I understand it correctly, that would make them 25.5” tall.

Fiero:
The tires that are on the ’86 Fiero are 225/60/r14 on the stock 14” Fiero rim. (same size all the way around)

When I checked various tire measurement sites (thanks to all the great posts with links btw. ) A friend from a different forum and I came up with the following:

TireRack lists 185/75R14 ‘87 Fiero and as a base. = 24.9” tall.
The same calculator says that a 225/60R14 would be slightly shorter at 24.6".
The 235/40R18 is about 25.4" to 25.5” (depending on the calculator used).

Another calculator lists it this way:
If the speedometer says the car is going 60mph with factory wheels 185/75/r14, the ground speed (what a cop sees) is listed below

185/75R14 = 60.0mph
225/60R14 = 59.3mph (car moving slower than Fiero speedo says, but better for acceleration and braking)

Now plugging various 18” sizes:
215/40R18 = 59.6mph (matches current 225/60/r14 ones, but low sidewall means easier to bend rims)
225/40R18 = 60.4mph (good match according to calculator)
235/40R18 = 61.2mph (The combo in question: car is moving faster, but heavier for accelerating)
245/45R18 = 64.2mph (My friend fears this is almost as tall as a pickup truck or minivan tire. Are those fears justified?)

Now my questions:

Will the 235/40R18 + 18”/+35 offset combo fit a ’86 Fiero? How about ’88?
Will the wheels rub? Front/Back?
Turning radius?
How do I find the bolts that would go with these rims? Do I use the Fiero bolts, or do I have to find matching bolts? How do I do that? (I remember that both my parents’ cars have sets of bolts for each set of rims (summer/winter tires) but these came with the rims when we ordered them)
Where do I get some electronic device that corrects the speedo? How much are they? How do they get installed?

Subjective questions:
Will they look good?/Out of place?
How will handling be affected?
Is there a glaringly obvious question that I forgot to ask? Please let me know.

The offset, size, and overall diameter should be fine for your car.

They would look ridiculous on an 88 (the fronts will stick an inch out of the fender).

Steering effort will be increased. Your brakes will look puny underneath but some 13" rotors would look great ;-).

Go with a smaller width on the front but the close to the same overall diameter (215/40R18 will be good). You don't need a fat tire up front, the car will handle better with equal contact pressures front and rear which means keeping tire width the same proportionally as your weight distribution.

I run a 245/40ZR18 on a 18x8". I believe that is within spec by 3%. Not all speedos read the same. By federal law they can be up to 3% off in either direction.
Dave
forgot to mention, I run coil overs to get the proper clearance.

[This message has been edited by bmwguru (edited 03-11-2008).]

quote Originally posted by bmwguru: I run a 245/40ZR18 on a 18x8". I believe that is within spec by 3%. Not all speedos read the same. By federal law they can be up to 3% off in either direction. Dave forgot to mention, I run coil overs to get the proper clearance.

You missed something important... what's the offset on your 18x8 rims?

quote Originally posted by Steven Snyder: You missed something important... what's the offset on your 18x8 rims?

sorry....it has a 38 offset....here is a pic

35mm offset works. Looks good if you ask me. Some people say they will stick out but I don't think it does too much. I have an 87 with coilovers 18x8s with 245/40/18. Can't tell you if the speedo is off cause my speedo doesn't work.

quote Originally posted by bmwguru: here is a pic

Yow-zaaa!!

quote Originally posted by bmwguru: sorry....it has a 38 offset....here is a pic

Thanks! Your car looks great. Is it an 88?
I would go with much more offset on the front; the rims do stick out past the fenders. (Easier would probably be to just use a 7" wide rim up front with ~38-45mm offset). For an 88 Fiero on the front you need even more offset.. about 10mm more.

Yeah those wheels will work, 225/40/18 are on the front of mine, with 235's on the rear. steering response is alot quicker than stock sized tires at higher speeds.

quote Originally posted by Steven Snyder: Thanks! Your car looks great. Is it an 88? I would go with much more offset on the front; the rims do stick out past the fenders. (Easier would probably be to just use a 7" wide rim up front with ~38-45mm offset). For an 88 Fiero on the front you need even more offset.. about 10mm more.

No, that's a 1987 GT. The rims only come in a 18" and bigger, so the 17x7 wasn't an option. It really doesn't stick out, the car just came off the lift and the suspension hadn't settled yet, so the camber might be a little out in the pic.
Dave

Thanks guys.

Your feedback helps a lot.

Why do wheels have to be staggered anyways? GT's tend to have wider wheels in the back, but Notchback SE's are the same tire with all the way around.
What's the downside of using the same with all the way around (the way the car is stock)?

So will 235's work in the front?

Steven S., you're right. The stock brakes would probably look puny. <-- *insert Arnold Schwartzenegger voice here *

I would love to use something like 13" brakes with these. I'm still learning about all the intricacies involved with slapping on bigger brakes. Things like "brake bias" really worry me.
I just need to find a way I can afford big brakes.
Non '88's seem to be very expensive. (at least in "kit" form. ) I saw threads mentioning DIY 13" adapters with Corvette calipers for non '88's, but couldn't find all the necessary details.

[This message has been edited by Austrian Import (edited 03-13-2008).]

After digging through Fiero website archives I have another rim question:
http://fiero.cc/fiero-tdc/m...s/Boxster/index.html

Do I have to worry about finding a hub centric ring for aftermarket wheels? (if the centerbore is much larger than on the Fiero)

I've seen hub centric rings for big brake kits, saying they're important so the weight isn't carried on the studs. Does the same apply for rims?

I do not have a picture of them, but my TSWs are hubbed larger than my spindles. I use a (i think it is) plastic adapter ring for the rim to fit on the hub. It is blue, and fits snuggly between the rim and the hub.

quote Originally posted by Tony Kania: I use a (i think it is) plastic adapter ring for the rim to fit on the hub. It is blue, and fits snuggly between the rim and the hub.

Only 1 person uses an adapter?

Fieros are so light in the nose that you can do just fine with a 215 up front.

The hub ring for the brakes is to have the rotor centered, usually made out of steel or aluminum. IIRC

The hub rings for wheels arent a necessity, also helps with keeping the wheel centered,meaning less shake/vibration

quote Originally posted by Austrian Import: Why do wheels have to be staggered anyways? GT's tend to have wider wheels in the back, but Notchback SE's are the same tire with all the way around. What's the downside of using the same with all the way around (the way the car is stock)?

I don't know if you had this question answered or not, it was asked quite some time ago...

Anyway... without power steering the effort in turning the wheels obviously goes up. With the stock 14's the width is only 5 inches... The GT lace wheels are 15x7 on pre-88 Fieros all the way around and to reduce steering effort they used a tire with a smaller width up front. Generally going to a wider tire/rim up front will increase steering effort. That is an argument for using staggered wheel diameters on the car as well... 17x7/7.5 in front and 18x8/8.5 in the back for example

On the 88s the GT/Formula fronts are actually 15x6 but use the same size front tires as the previous years... it gives the 88 a slightly different tire profile due to the narrower wheel. I believe this is one of the reasons that a lot of the 88 GT/Formulas look like they are dragging thier butts. That combined with the different geometry up front gives noticably easier steering than the previous years.

Also that 15x6 on the front of the 88 is a PITA not only because the offset is different than the rear it is also a relatively high/rare offset.

[This message has been edited by carbon (edited 07-07-2009).]

quote Originally posted by Isolde: Fieros are so light in the nose that you can do just fine with a 215 up front.

I did 215 up front with 17's. It really improved the steering, making it lighter and more responsive.

Tire Size Calculator if you need it.
http://www.miata.net/garage/tirecalc.html

It should be noted that a 215/45R17 will still give you a wider contact patch than a 225/60R14

quote Originally posted by Isolde: It should be noted that a 215/45R17 will still give you a wider contact patch than a 225/60R14

That's good to know.
So with 235/45/18 I'll have a really wide patch up front then. (with a very light front end on top of that..)

quote Originally posted by Coinage: The hub ring for the brakes is to have the rotor centered, usually made out of steel or aluminum. IIRC The hub rings for wheels arent a necessity, also helps with keeping the wheel centered,meaning less shake/vibration

So even though they aren't necessary for rims, they're a good idea?
Where do I get them?

Is there really only 1 person that uses these plastic/(metal?) hub rings for rims?

For this manufacturer, you will have to know the manufacturer of your wheels.....( A lot of people buy Ebay wheels with no brand name )

http://www.justforwheels.co...earch&cat=hubcentric