Front track with 1-in wider than rear track with. Will this cause any issues?

[Schroeder]

I widened my front tires to get more of a deep dish look on my '77 trans am. Now the front track width is about 1-in wider than the rear. Will this cause any issues? I found some threads online with inconclusive evidence. There was a very detailed, good thread on an engineering forum. They went back and forth with the equations and models. There wasn't ever a definitive answer on whether it mattered or not. There are so many variables.

I have a Detroit speed quadrille rear end with Moser axles. These are already not hubcentric axles. Their lug centric. I don't really want to put a half inch spacer on each axle to bring them out. I also have to flare my quarters a bit too much to the point where they look a bit odd if I am going to put this 1/2 in spacer on either side. So the question is does the slightly narrower rear track width matter? Will a half inch spacer on the rear ends matter in a setup that is not hubcentric?

[dontlifttoshift]

Are you measuring track width or from outside to outside of the tires? Mostly a curiosity as every one does it different it seems.

Anyways, not an issue. I certainly wouldn't run spacers and flare 1/4 panels just to get to a matching number.

[CSG]

It will decrease the understeer when you make the front wider or the rear narrower. Is it enough to tell in the real world? I don't know...
I have done it on off road vehicles and it was noticeable but my percentage of change was larger than what you have.

[Schroeder]

Are you measuring track width or from outside to outside of the tires? Mostly a curiosity as every one does it different it seems.

Anyways, not an issue. I certainly wouldn't run spacers and flare 1/4 panels just to get to a matching number.

I am measuring from the outside of the tire to the outside of the tire. Yeah, I do not believe that spacers are as bad as people say they are when the bolts are torqued correctly. I would get into the debate a little bit when you consider the fact that the spacers and wheels are not subcentric though. That aside, I agree with you. The flares are a little excessive when going out so far that I have to run a half inch spacer just to match a number. I already have to flare a little bit and I'm okay with that because it's subtle. The amount to get the half inch spacer to fit though becomes unsubtle where the flare doesn't look that great in my opinion. It's too gaudy. I want the flare to be noticeable, but I don't want it to look like I'm trying to make the trans am fit in with the JDM crowd.




It will decrease the understeer when you make the front wider or the rear narrower. Is it enough to tell in the real world? I don't know...
I have done it on off road vehicles and it was noticeable but my percentage of change was larger than what you have.


Thanks a lot. I assume your assessment is correct. I'm guessing someone that races often or races for a living might be able to tell with the difference I'm talking about. I am not in the everyday racer crowd. I can't believe I'll imagine any performance difference.

[stab6902]

I wouldn't worry about it either - your new wider front tires will have more of an impact on your car's balance than a small increase in outside of tire to outside of tire width. There are a lot of other ways I'd try to balance the car before resorting to wheel spacers.

[Schroeder]

I wouldn't worry about it either - your new wider front tires will have more of an impact on your car's balance than a small increase in outside of tire to outside of tire width. There are a lot of other ways I'd try to balance the car before resorting to wheel spacers.

Thanks. Can you elaborate on how the wider front will affect balance?

[stab6902]

Wider tires in the front will make the car "looser" - more prone to oversteer - than it was before, all other things equal. Too much front grip is rarely an issue in these cars.

A wider front track width (center to center of tires) will reduce roll stiffness since the wheel will have more leverage on the spring. Increasing track width will increase grip at that end of the car.

Just putting wider tires on the same wheels will not increase track width (by it's official definition - center to center) since the tires will stick out the same distance on the inside as the outside.

[Schroeder]

Wider tires in the front will make the car "looser" - more prone to oversteer - than it was before, all other things equal. Too much front grip is rarely an issue in these cars.

A wider front track width (center to center of tires) will reduce roll stiffness since the wheel will have more leverage on the spring. Increasing track width will increase grip at that end of the car.

Just putting wider tires on the same wheels will not increase track width (by it's official definition - center to center) since the tires will stick out the same distance on the inside as the outside.


Thanks for the scientific explanation. Love it.