do you need spacers for c5 wheels on 99 firebird

**jefff82** · 05-06-2014, 02:38 AM

i have a 99 formula. found a smoking deal on some c5 thin spoke wheels with tires. ive read that you need spacers and have read that you don't need them. looking to get a definite answer to see if I need to buy spacers or not. the wheels are the 17 in front 18 in the rear 5 spoke wheels off a 03 corvette I believe.

**bigrondownhiller** · 05-07-2014, 01:05 PM

No spacers needed. You might trigger the abs light with the difference in diameter though.

**jefff82** · 05-07-2014, 01:14 PM

Originally Posted by bigrondownhiller

No spacers needed. You might trigger the abs light with the difference in diameter though.

Why would rims mess with abs

**bigrondownhiller** · 05-07-2014, 01:26 PM

Its the difference in overall diameter between the front and rear that causes the problems.

**jefff82** · 05-07-2014, 01:32 PM

never thought of that. have seen so many birds/Camaros running these didn't think there would be any issues. what problems does it cause. I hate dash lights

**bigrondownhiller** · 05-07-2014, 01:39 PM

I guess some people don't mind it. Probably the light and lack of abs.

**jefff82** · 05-07-2014, 01:44 PM

Originally Posted by bigrondownhiller

I guess some people don't mind it. Probably the light and lack of abs.

can u fix it so the lights don't pop up without changing the wheels back to stock

**bigrondownhiller** · 05-07-2014, 01:50 PM

I haven't heard of anyone doing it. If you put a tall enough tire on the front to keep the difference minimal you should be fine.

**jefff82** · 05-07-2014, 02:02 PM

Originally Posted by bigrondownhiller

I haven't heard of anyone doing it. If you put a tall enough tire on the front to keep the difference minimal you should be fine.

I did the math with the 245 45 17 = 25.68
275 40 18 = 26.66

will that make the light come on you think

275 35 18 = 25.57

does it matter if I go thinner in rear. the rears will be replaced first

**bigrondownhiller** · 05-07-2014, 02:18 PM

If you go with the 275 35 18 in the rear you shouldn't have a problem, only .1 inch difference. With the 40 series there is an inch difference. You should also check the specs on the tires you are going with. There might be a slight difference.

**jefff82** · 05-07-2014, 02:22 PM

difference in what specs

**bigrondownhiller** · 05-07-2014, 02:27 PM

The actual diameter depending on tread depth. It will probably be miniscule though.

**jefff82** · 05-07-2014, 02:46 PM

thanks I would have been mad seeing my lights coming on and not knowing why. found some 275 35 18 tires for 270 out the door mounted and balanced. that was the best I could find

**bigrondownhiller** · 05-07-2014, 03:00 PM

Just look for some pictures of cars with the different rims. Make sure you like the look with the shorter sidewall tire on the rear. Not sure if you will be able to see a difference.

**b.lee** · 05-07-2014, 04:54 PM

Youll need to do the BFH mod to the rear inner fender wells.
Aka pound in a little portion of the inner fender wells to clear the rear tires when hitting bumps

**sjgreen6** · 05-08-2014, 02:39 PM

I'm running the N73 wheels with Nitto 555 tires in 245/45ZR-17 and 275/35ZR-18 with no problems at all. The overall diameters on the front and rear are close enough that I have not had any issues with traction control or braking. The N73s have a slightly different backspacing than yours which puts them inboard a little more but I have not had any issues with rubbing or bumping the suspension.

**jefff82** · 05-12-2014, 01:06 AM

So the wheels do rub on bumps. Has any body ran adapters. If so how big. And do you have trim the studs down. Was looking at a 1" adapter but didn't know if stock studswould be too long. Don't want to trim down studs. Will the 275 stick out too far with the adapters

**sjgreen6** · 05-12-2014, 02:40 AM

If you are talking about rubbing on the inside against the wheel well, as b.lee posted, you might be able to make adjustments with a soft mallet on the wheel well. Make sure if you accidentally remove any paint that you recover it to prevent future rust. Also, are you using the taller bump stops that come stock on cars with 17 inch wheels? All of the SS and WS6 cars have taller bump stops than the cars with 16 inch wheels to help prevent rubbing. You can get these aftermarket in rubber or poly urethane with the correct spacers.

**jefff82** · 05-12-2014, 02:51 AM

Originally Posted by sjgreen6

If you are talking about rubbing on the inside against the wheel well, as b.lee posted, you might be able to make adjustments with a soft mallet on the wheel well. InMake sure if you accidentally remove any paint that you recover it to prevent future rust. Also, are you using the taller bump stops that come stock on cars with 17 inch wheels? All of the SS and WS6 cars have taller bump stops than the cars with 16 inch wheels to help prevent rubbing. You can get these aftermarket in rubber or poly urethane with the correct spacers.

Mine came with 16's stock. So stock bumpstops.would rather space it out than beat the inner fender well I guess

**sjgreen6** · 05-14-2014, 05:43 AM

It might be a cheap solution to your problem without breaking out the hammer. I'm not sure if any of our sponsors carry they but you can get them from KY Speed for a little more than $25.00. They are just a bracket that sits under your current bumper to increase the contact height. All of the 4th Gen F bodies that came with 17 inch wheels had them from the factory.