Tire/Wheel Stagger Question

[bvarianlvr]

All,

Thanks in advance for any enlightenment you can provide.

This question occurred to me the other day in regards to staggering wheels.

Are the outside edges of the tires and wheels equidistant in front and rear?

Or are the inside edges equidistant?

Or are the centers equidistant?

The reason I ask is due to the fact that they say that staggered setups understeer. I think that if the outside edges are equidistant, then that understeer would be neutralized. No?

[KarlSpackler]

So what are you suggesting. I believe the centers are equidistant on a normal staggered setup.

Are you saying like run wider wheels in the rear with a higher offset to bring them back toward the car???? Enlighten me

[elh0102]

I think, in the case of the E46 M3, the offset is designed to give the same track, as measured from the centerline of the wheels. But any minimal difference in track you make with different offsets, is not nearly as significant as the difference in tire size. To offset the understeer, going to a larger front tire makes a significant difference. I'm using all 255/40-18 on an E46 M3, and that change made a big difference. Since the wheels are all the same, I'm using a 15mm spacer in the rear, which restores most of the 20mm difference in front and rear track.

[KarlSpackler]

I think, in the case of the E46 M3, the offset is designed to give the same track, as measured from the centerline of the wheels. But any minimal difference in track you make with different offsets, is not nearly as significant as the difference in tire size. To offset the understeer, going to a larger front tire makes a significant difference. I'm using all 255/40-18 on an E46 M3, and that change made a big difference. Since the wheels are all the same, I'm using a 15mm spacer in the rear, which restores most of the 20mm difference in front and rear track.

How would your set up differ in handling from a staggered set up.

By running spacers and the same tire size all around, you are pushing the rear wheels out further from the hub. This is the same reason that a staggered set up will understear.

I say run the same size wheels and offsets all around, then stagger your tires. If this is not correct, someone please tell me a better set up for auto-x

[elh0102]

How would your set up differ in handling from a staggered set up.

By running spacers and the same tire size all around, you are pushing the rear wheels out further from the hub. This is the same reason that a staggered set up will understear.

I say run the same size wheels and offsets all around, then stagger your tires. If this is not correct, someone please tell me a better set up for auto-x

You have to remember, the track of the E46 M3 is not staggered. Because of the bastard arrangement of the rear suspension, the tracks, as measured from the hubs, are staggered, with the rear being about 20mm narrower. So, by using about 20mm less offset in the rear, the car ends up square. And in my experience, a 20mm difference in offset, staggered or not, will not have near the effect on handling balance as going to a 30mm wider tire in front, making it the same as the rear.

[bvarianlvr]

So what are you suggesting. I believe the centers are equidistant on a normal staggered setup.

Are you saying like run wider wheels in the rear with a higher offset to bring them back toward the car???? Enlighten me
I definitely don't want a staggered setup. It was just a question I had that I thought I'd have answered.

I was just wondering this because my BBS RK's have a 13mm offset, way too low for the rears after lowering the car. I had to have the fenders rolled. I found it ridiculous that Tire Rack didn't warn of this from the get go. I think those were meant to be staggered since they're just fine up front, no fender rolling needed. I think the rears would have been a 20mm offset or something to avoid rubbing. That's what made me wonder if the outside edges were equidistant front and rear.

Also, those wheels have summer tires on, and I'm back on the OE Sport package wheels for the winter. But once I had them put back on, steering effort, acceleration, ease of getting up to high speeds were WAY better than with the RK's.

Does that mean the offset is incorrect for optomized performance for my car? I'm considering selling the RK's for this reason and getting some wheels with a 20-22 mm offset, which would be optimal for the extra width I'd be getting over the OE wheels.

Sure, a stuffed fenderwell looks good, but I'm more into optimizing my car's capabilities, rather than going for looks.

Thanks,
J