Wide Wheels and Tires = Why is this so difficult for me?


Well-Known Member
Geez, I thought selecting a nice staggered wheel and tire setup years back for my 2009 Pontiac G8 GT was difficult given the odd bolt circle (5x120 - not 5x120.65 aka 5x4.75), the front Brembo brake clearance concerns, the rear fender lip and the BMW-like offsets.

Deciding on new wheels and tires for the GN seems to be a problem for me AND I'm a wheel and tire guy, meaning, I understand offsets, backspacing, clearances, etc...

I need help from all of you who have done this before me.

Goals & some Questions:

1. Mostly for street driving/meets/cruises - widest looking wheels and tires (wider than 275s) in rear and front that still look muscle. I'm not into the pro-street or touring look for the GN. I want to stay on 15" wheels. I can keep my existing stock rims and MT 255/60 drag radial for track days so the tire I'm looking for can be a true street radial or a drag radial, it shouldn't matter. Only the size matters BUT no rubbing. I'm not into bias ply.
2. Preference is a level ride height. Worse case a slight rake but I don't want it to look jacked-up in the back.
3. Max tire diameter in rear is 28", minimum is 26". Front tire diameter should match, I think??? Maybe .5" less max???
4. Rims will be lightweight aluminum, probably something from Center Line, i.e. Rev or Billet series.
5. Leave car height stock. I have new springs, Kirban cargo style in rear, new Bilsteins, HRParts bar, HRParts upper & lower arms, all kinds of rear and front bracing, etc. Shouldn't be that much movement in the rear but I don't have air bags. I also have stock Aluminum rear brake drums.
6. I will not notch the frame. I will not cut fenders or any body panels.
7. I am open to rolling the fender lips as I had this done on my G8 so I'm not concerned. BUT... I don't see how the rolling on the GN happens easily given that fender opening trim that screws to the lip???
8. I have no issues with spacers or wheel adapters if needed but prefer to avoid.
9. I bought GNX fender flares. Trying to figure out how the heck these fit into the equation. Can a wide 26" tall tire leave enough room with my rear suspension mods to NOT smash up into the flare if I get an offset that pushes the wheel/tire out under the flare? Will that look like crap? Will a 28" tire never work under the GNX fender flare? I like a wide-body look or a nearly flush look. I don't prefer the look of narrower tires, all kinds of space between the tire and the outside fender and it makes the car look like it wants to tip over onto its side. So, either a) tire and offset to sit flush with GN fenders OR b) tire and offset that moves out further and fills the GNX fender flares.
10. Not a huge fan of the skinny look in front. I want the car to sit as close to level as possible and I like the GNX look when the front tire sits almost flush and has some width to it, i.e. 245mm.

The Tall Rear Tire Option and what about the front...

MT ET Street SS 295/55-15 on 15x10 4.5" backspace. I've seen guys here do this and fit ranges from nothing needed to slight lip roll. That is nearly a 28" tire. What do I do about the front tire so the car doesn't look like it's facing downhill? 28" MT Sportsman S/R on a 7" or 8" rim? They have them in 8" and 10" wide. Not the best options for a front tire. This same tire is also available in 26" but with a 28" rear tire, this will defeat my goal of not having the car look slanted. I could run a 245/60-15 or 255/60-15 BFG Radial TA on the front which are closer to 27" to bring the front up and get some meat in the front like the GNX. But I wonder what problems a tire this tall and wide will cause with turning and/or rubbing? With proper backspace, I can bring the front tire inward or outward. Most likely outward like the GNX with that wide of a front tire. Again, I have GNX flares to cover these if they stick out.

The Short Rear Tire Option and front...

MT Sportsman S/R 26x12r15 (which is about 305mm wide) on 15x10 4.5" backspace. I've seen one guy here use the 28x12 and he wasn't happy with it (too wide). This wide tire will stick outward for sure but I have the GNX flares if needed. My main point for considering these is at only 26.1" diameter, this might give me all of the clearance I need to NOT bang the tire up into the GNX flare or the stock lip for that matter. But it is VERY wide and I hope this doesn't cause me other problems. For front tires, I can either go with the matching diameter Sportsman 26x8 (but its only 215mm wide and I wanted more) or the 26x10 which is about 265mm wide which probably won't work on the front of a GN??? The other option for the front is a 235/60-15 BFG Radial TA which is also 26.1" diameter and clears fine as I have that size today. With a new 8" front rim, I'd pick an offset that moves it outward a little for flush look or to fill the GNX fender flares.

So, that is my dilemma. Each path has "hair."

Tall, wide, less level, possible fender or GNX flare interference.


Shorter, wider & riskier, level, possible less fender or GNX flare interference just due to shorter height.

Guys, please help me through this and slap some sense into me if need be. Remember, this is for looks and street cruising. This is not a drag strip setup.

Thank you!
You said it your a tire and wheel guy and after reading the whole thing you have answered your own questions. GL
You said it your a tire and wheel guy and after reading the whole thing you have answered your own questions. GL

I guess. LOL. I just wished I felt 100% on either option. Sometimes it's just cathartic to express it to a group of awesome TR guys who have 15X the experience I do. Right now, my ideas are on paper and I'm at this 2 years. You guys have lived and breathed this for 30 years in some cases.

My sense is "some" guys on this forum might get tired of answering what seems to be the same questions over and over again for the new guys. I was the tire and wheel guru on 2 G8 forums for nearly 7 years but I always made time to answer the newbie questions even though the data existed via stickies and searching.

So bear with me guys. In short time, I'll be answering the newbie questions for you guys so you can relax :)

My post is with all respect as I know you are a great member here.

Definitely interested in more or alternate opinions and experiences. As much as I think I know, I'm never too proud to ask for advice.
I haven't ran 15's in years, I've had 17's for quite a long time. For sure you are limited on sizes and as the years go by it may be more so? Hey even 17's is getting limited. these days.

I'm sure a few other guys that still run the 15's will chime in.

Whatever you choose be sure to post up a pic I would be interested in seeing the stance. Good luck
15x9 with 4.5 backspacing works well. I run those with the 295/55's, and my car sits low. Minor trim or rolling of the lip, depending on how low your car sits. If it's up in the rear then no trimming at all.

For fronts, I've run 215/70's on 15x7's in the past. They're about 27 diameter. A 3.5 or 4 inch backspace works well.