confused on wheel setup

[Aproductions]

I have some 17" wheels for my GSX

They are staggered 8" front and 9" in back....would I run the same tire size all the way around so my speedo stays the same?

I was thinking 225/45/17 (little bit of stretch look)

Also will this hurt my AWD in any way?

 

[jtmcinder]

Before I forget, you might want to update your profile to reflect that your GST is now AWD. I was close to suggesting that the wider wheels belong on the front, given that your car is both front-heavy and FWD.

With the above out of the way, if you insist on staggered wheels on an AWD with a 50/50 center and equal gearing, then the wider wheels go on the front. [tee hee] Put 245/40/17s on both sets of wheels. The wider front wheels will give you more lateral grip, making it possible to get your 3200# pig to turn. The thinner wheels on the rear will also help in this regard, albeit by lowering grip (which should always be a last resort).

ps. buried inside all this is the one good argument that I've ever seen for staggered wheels on an AWD DSM. One overlooked aspect of handling, especially on typical roads, is the ratio of unsprung to sprung weight for a given corner of the car. As this ratio goes up, more vertical movement over bumps is transmitted to the chassis. Since the rear of a DSM weighs so much less than the front, lighter rear wheels are a plus. On the assumption that the OP's 17x8s weigh less than his 17x9s, putting the 17x8s in the rear will make for better grip and ride quality on non-perfect roads.

 

[Aproductions]

Thanks for that. I am only using these wheels as cruising/show wheels, I am getting lighter ones for the track. That being said, will anything bad happen using the same size tire all around and have the 9" in the BACK? (looks better)

 

[jtmcinder]

The working diameter of a 245/40/17 tire will be a tiny bit smaller on a 17x8 than a 17x9, but not by enough to matter. When you did the AWD swap, did you include a center VC? If so, then that's the only thing that would "care" about slightly different diameters for the tires, but, again, the difference for 245/40s on those two wheels will be small enough to have no real effect.

Please don't put 225s on a 9" wheel. I know that the hella stretched look is this decade's fuzzy dice, but take it from someone who lived through the fuzzy dice era: we're all embarrassed about it now.

 

[Aproductions]

I just need my speedo to be accurate.

So what would be the ideal in the front 17x8 and the back 17x9?


Also I am still in the middle of the swap but I have a lsd rear diff, and a stock 1997-1999 transmission.

 

[jtmcinder]

I just need my speedo to be accurate.

Then it's time to sell the DSM, because they are never accurate.

245/40/17 will make it read even more high than it did with OE-sized tires. But not enough to really matter. I'll bet you're already driving a few over the limit, anyway.

So what would be the ideal in the front 17x8 and the back 17x9?

I'd do 245/40/17 on both sets of wheels, regardless of whether you stagger them for performance (wider in front) or looks (wider in rear).

Also I am still in the middle of the swap but I have a lsd rear diff, and a stock 1997-1999 transmission.

It's the center's VC that would care about different diameters, not the rear's VC. But, again, 245/40s on 17x8s vs 17x9s isn't going to be different enough to kill a center VC.

 

[Aproductions]

Okay, thanks for the help.

Now if I have a stock setup would that mean:

my diffs are:

front-open
center-open
rear-LSD

 

[jtmcinder]

Not quite. If you take an unmolested AWD tranny and put it in as it was, you'll almost definitely have a VC on the center. It's the rear that you really have to check. The front will be open.

I'm almost sorry that I brought the issue up, because I seem to have worried you. Seriously. If you put identical tires on 8"- and 9"-wide wheels, their effective diameter will be close enough to not hurt a center VC, at least with 245/40s.

 

[ACM]

I would just add that killing a VC is not a big deal - they cost peanuts and theyre easy to replace. A bigger concern is the stock centre diff, with the bronze-coated shims baking up the end gears. These don't like being used, and respond by shedding their bronze and welding themselves to either the diff housing or the back of the gear. By then your tranny is essentially trashed from all the bits of crap that get flushed through all the other parts.

This is the reason for the Torrington bearing conversion in 4-spider centre diffs.

 

[jtmcinder]

Now that Charles is here, I'm going to risk confusing the OP by making a crazy suggestion.

People seem to want to create showy cars with wheels that are staggered to the rear, but that makes no sense on a front-heavy car with a 50/50 center. Given that the AWD swap hasn't been done yet, why not create something unique and potentially road-worthy? Get a rear-biased planetary center, such as the Cusco Tarmac diff, omit the VC (as Charles has shown to work fine), and run rear-staggered wheels AND tires. You could have 245/40/17s on the 8"-wide wheels in the front and 275/35/17s on the 9"-wide wheels in the rear. (These are actually close enough that you could keep the VC, if you wish.) In contrast to 99% of all staggered AWDs that you see at shows, which are staggered to the rear with a 50/50 center, which makes no sense at all, this car would be staggered to the rear and actually make sense to be that way.