Just wondered if there is any problem with putting the honeycomb wheels from an 87 or 88 (know the 88 are different size/offset front/rear) on my 85GT?

I think they are from an 87GT but have not found out for sure yet. I know the speedo will be affected just want to know if they will fit on the hubs ok. I currently have the normal 14" GM wheels that came on the GT's.

no problem

Nope, just did it on 2 of mine.

Thanks all. I just bought four wheels and new tires off craigslist for $125.
He could not find the date code so I'm not sure the age of the tires but for the money I can always buy new.
I was interested in some stock type rims and the 15" will give me 1" more diameter on the tires to drop the rpms a bit more than 14's.
Once I get the getrag 5sp in will drop it a bit more. I wanted to get the rpms dowm more for a road car since it's a daily driver.
The 3.4 gives me more low end torque so the tires will not hurt much. Plus the 4sp has such a quick 1st gear anyway..

Actually, you shouldn't much difference because the circumference of the rear tires will/should still be the same as the circumference of the tires from your fourteen inch wheels. If the circumference is not the same, the speedometer becomes inaccurate. The production date is only on one side of the tire, following the DOT stamp. What's the third segment of digits (should consist of three or four digits) after the DOT stamp?

If they are from an 88 the front rims will have a different offset from the rear ones. 87 offsets are the same front and rear

theyll fit. i did this on my old SE it dident even mess up the speedo.

Wheels will fit. Speedo gear may need changing, depending on tire size https://www.fiero.nl/forum/Forum2/HTML/093414.html

On my Indy, I changed from the stock 14" wheel with P215/60R14 tires to 15" wheel with taller P215/60R15 tires and needed to change the speedo gear.

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World of Wheels Winners
My 3.4L S/C 87 GT
& Super Duty 4 Indy

I measured the diameter of the wheels on my 88GT compared to the 14" wheels on the 85GT and there was 1" difference.
If all my math is correct that is just a little over 4% difference. So hope it will drop about 100rpms. On a 1200 miles trip that adds up.

If you have a coupe, with tall thin tires on its 14-inch wheels, the change won't make a difference. But if you have a car like an 85 GT, with 215/60R14 tires on it, going to 215/60R15 will make a difference.

Exactly!

That's a TopNotch answer...

[This message has been edited by Dodgerunner (edited 08-11-2009).]

quote Originally posted by Dodgerunner: I was interested in some stock type rims and the 15" will give me 1" more diameter on the tires to drop the rpms a bit more than 14's.

quote Originally posted by Dodgerunner: I measured the diameter of the wheels on my 88GT compared to the 14" wheels on the 85GT and there was 1" difference. If all my math is correct that is just a little over 4% difference. So hope it will drop about 100rpms. On a 1200 miles trip that adds up.

Your math may be fine, but the logic behind it unfortunately is not.

Just so you know, it's tire diameter or circumference --- rather than rim diameter or circumference --- that will affect your RPMs at any given speed, and thus your mileage.

The same is true for affecting your speedometer.

More specifically, regardless of the engine in it (e.g., whether your 3.4L engine swap or anything else), your Fiero's RPMs are a mathematical function of your car's speed (expressed here in MPH), its final drive ratio (FDR), and its rear tire diameter (TD) expressed here in inches:

RPM = [336 x FDR x MPH]/TD
As you can see from the above equation, the car's rim size --- to which you've referred a couple of times --- simply is not a factor in determining the expected RPM levels for it. It's the rear tire size that is the issue.

You've probably posted a bazillion useful things for others of us on this forum in the past --- a "bazillion" being my very unscientific mathematical term rather than yours --- and hopefully the specificity of my response in some way helps return the favor.

I've had the '88GT wheels on my '85GT for 15000 miles with no issues. I do have tires on them that match the O.D. of the stock 14" tires (215-60x14 = 24.2" OD).





I used 225-50x15 (24" OD) rear and 195-60x15 (24.2" OD) on the front, Yokohoma ES100 tires

For the record, I've heard that every Fiero wheel will fit every year Fiero except the 13" wheels won't fit over the '88 brakes.

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RickN
White 88GT 5spd
White 85GT Auto
White 99 F250SD 7.3PSD 6spd
1956 Ford 860 Tractor w/ Freeman Loader
20Ft Tilt Bed Trailer

[This message has been edited by RickN (edited 08-11-2009).]

Thanks project34 I am using the outside tire measurement for my calc. not the rim difference. I measured my 85 tires and my 88 tires and that is the difference I found in my case.

DR I have switched the two types of wheels both ways before, and have not had any issues. I have 87 Honeycombs mounted on my 88 coupe right now. Havent driven it yet.
Joe

Well I'm sure they will work. I'll know for sure after Sunday after I pick them up.
I could have swapped them off my 88 if I really wanted to try them but am sure enough I didn't.

[This message has been edited by Dodgerunner (edited 08-11-2009).]