[Ozz1967]

Hey guys,

I'm putting a new engine in my Trans Am and one of the things that goes along with that is upgrading my braking. I currently have 4-wheel disk but I want to dump my current 15-inch wheels as well as my stock spindles and go with something larger to help stop better.

I would like to put 17-18 inch wheels on the car, but I don't know where I can get spindles to match? Could I pull a set out of a corvette or maybe a truck that would fit?

Also, with getting larger wheels, how much wider could I go before I run into turn-radious problems...right now I have 15X7 inch wheels. Could I go to a 17X9 or even 18X9 or 10 inch wide wheel or will that hit the inner fender when I turn?

[farna]

You don't need different spindles for larger wheels. Order the wheels that fit -- not hard at all. If you get larger rotors you'll need new hubs, but not necessarily spindles. Depends on the brake kit. Check with brake suppliers. Larger wheels are required to fit larger diameter brake rotors and still clear the wheels.

Check some Camaro/Firebird sites for wheel width (www.f-body.org, www.f-body.com). You can easily go up 1", I'm not sure about more.

[yesgo]

I don't know how much this will help, but the 3rd generation Fbody like yours with 16" wheels used 16x8 with different offsets front and rear. The rears had a backspace of 5", and the fronts had a backspace of 4.33". You would probably need to keep close to the same backspace with wider rims to not hit the inner fender, which will push the offset inward so the wheel would stick out further, possibly hitting the fender lip if too wide. Also, the further you get from zero on the offset, the more problems you can develop with bearing wear and alignment/radius issues. (Zero offset on an 8" rim is 4.5" backspace).

Since you mentioned using different spindles, I guess that could change your backspace requirements. You could just use your current spindles or maybe an aftermarket spindle made for your car to use bigger brakes. The spindle itself generally doesn't care about the rim diameter. Overall wheel+tire diameter, backspace/offset, and width, as well as caliper/brake fitment are the major issues I think.
http://www.rsracing.com/tech-wheel.html#backspace

[Ozz1967]

I know that to support the bigger calipers, I need bigger wheels. However,to run them properly, I need larger spindles to hold them unless someone knows something different. I'm hoping a chevy truck or corvette might have what I'm looking for.

[curtis73]

Absolutely not. There are no spindles that swap into your F-body except other F-body spindles anyway so forget it

Although I don't recommend it, I've seen 22" wheels under F-bodies. It has nothing to do with spindles, its just ordering wheels with the proper offset in the size you want.

The 1LE and WS6 RPO codes are your new best friends. They came with four wheel discs that were 11" and 12" rear and front. Junkyard swaps are plentiful. After that you're looking at aftermarket. Wilwood makes a killer kit with 13" rotors all around but they require 16" wheels or more. The brake manufacturer will advise you on what size wheels you'll need.

Depending on what year the T/A is, you won't be able to go too wide. Look for 8 or 9" max, but its not the wheels that hit, its the tires. 245mm rubber fits but in most cases it rubs pretty good. My buddy's 84 T/A has 245/50-16 at all four corners with Eibach springs. It rubs pretty good, but the tread hits the gentle curve of the inner fender well so its not very damaging. Where you get trouble is when the sidewall scrapes sheet metal. It makes short work of a $200 tire

[Ozz1967]

That's what I was looking for. Stock rotors are 10" I believe...if I could up that to 13 then I'm in there. Now, to find a wheel and tire combo that will fit...

[curtis73]

If I may suggest, do some searches at tire rack.com or similar for sizes in your range. I think you'll find clear advantages with 17". For handling purposes that is far more than adequate. I think 16" is optimal on F-bodies, but they may not clear the brakes depending on which ones you get.

Above 17" I think you'll notice rather severe ride quality issues, wheel bending issues, and unpredictable sidewall performance. Not to mention, wheel and tire packages get lighter the smaller the wheel is. The same tire and wheel style will weigh more at 245/45-17 than it does at 245/50-16.

17" tires are plentiful and cheap. They're made in all speed ratings, weather ratings, and tread styles. 18" and 19" might leave you selecting between the $300 race tire or the $250 Michelin Pilot.

[Ozz1967]

I've been looking at some aftermarket wheel places, the most notable is "Iforged"...friend of mine put some on his car and they are absolutely beautiful. Thing is, they make them to your specification so they are a bit on the pricey end of things. They've got 17x9" wheels which are some of the smallest they make (mostly make import wheels) but their tech rep said they can and will make them for me, I just need the size, back spacing, and all the clearance numbers.

My only issue, is how wide is too wide, or not wide enough. I don't want to get a larget wheel that's too skinny, nor do I want wheel that's so large I'll run into issue with turning and tire rub on the fenders.

[curtis73]

Let your tire width decide that. If you want 245mm rubber, I might choose an 8" wheel. Tire manufacturer websites list acceptable ranges for their tires. For instance http://www.michelinman.com/assets/pdfs/PilotXGTZ4.pdf shows the specs for a Pilot XGTz4. If you look at the 245/45-17 application it recommends 7.5"-9". To an extent, the middle is the best. Wider wheels (like 9" in this case) will tend to reduce sidewall compliance. This will tend to make the tire stiffer which means a tiny bit more lateral grip, but less predictable handling. Its an extremely fine line. Shoot for 8" and that will allow you to run anything from 235 to 265 or so.

[yesgo]

I agree. 245s on an 8" should be perfect on that car. Not so wide as to rub or stick out, and definitely not skinny. Just get the backspace right, front and rear.