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i'm considering running staggered wheels since 18x8 F/R sounds like a lot of contact patch in the front and will probably cause lots of understeer. As it is I can't see this car breaking loose in the turns, but you may as well make the handling as neutral as possible. I was thinking 17x7 (215mm width) front and 17x8 (245mm) rear would make a good setup for driving schools. Any larger and you run out of good tire choices.

And the stock wheels, while nice, come with Eagle RS-A's? One of the crappiest tires ever... just behind the Potenza RE92's. I really hope we get something better by production time!
 

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:agree: 100%.

I was trying to get some help at the SKY forum, but not coming up with much as to how to fine tune tire width and profile.

http://www.skyroadster.com/forums/showthread.php?t=1247

I'll be buying a 2007 Solstice and I'm hoping Pontiac will tune their tires a bit more precisely. I understand the benefit of simplicity to putting the same tire on all 4 corners, but my guess is there is too much tire up front with needless unsprung weight.
 

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I admit I love the idea of going to a wider rear tire for the looks and performance, but at the sime time I'm tire tuning stupid. It's all magic and voodoo to me. :D So I'm going to wait till the higher performance Solstice is released or Pontiac starts Racing the Solstice to look towards those as guidelines on what to do with the tires/wheels. Either that or someone puts out some compelling information towards a setup that would be ideal for this car.
 

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arm1tage said:
i'm considering running staggered wheels since 18x8 F/R sounds like a lot of contact patch in the front and will probably cause lots of understeer. As it is I can't see this car breaking loose in the turns, but you may as well make the handling as neutral as possible. I was thinking 17x7 (215mm width) front and 17x8 (245mm) rear would make a good setup for driving schools. Any larger and you run out of good tire choices.

And the stock wheels, while nice, come with Eagle RS-A's? One of the crappiest tires ever... just behind the Potenza RE92's. I really hope we get something better by production time!
Better drive the car first, then consult a professional. To illustrate, a larger contact patch in the front will increase front grip relative to the rear, thus REDUCING understeer. By going to a 7 in front and 8 in rear, you will exacerbate any understeering tendancies by further reducing front grip. Better drive the car first, then consult a professional.

As to tire choice, wholeheartedly agreed that a better tire will really make this car world class. Oh yeah, and another 50 hp or so.;)
 

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Breeze said:
Better drive the car first, then consult a professional. To illustrate, a larger contact patch in the front will increase front grip relative to the rear, thus REDUCING understeer. By going to a 7 in front and 8 in rear, you will exacerbate any understeering tendancies by further reducing front grip. Better drive the car first, then consult a professional.
:agree:

A large front contact patch will lower the understeer tendencies, not increase them.

Consider also that the vehicle dynamics are being done by professionals, people who get paid for their vehicle dynamics knowledge, and their ability to drive and tune a vehicle. Second guessing by armchair "experts" will quite often result in a vehicle that performs more poorly, not better than the production vehicle.
 

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I imagine GM figured since the gearheads are going to replace the all-seasons anyway, why waste money? Seriously, I have tires for everyday and tires for the track. All together, I have 11 wheels for one car...

Another good place to look to improve handling is in the suspension bushings. GM has a serious tendancy to trade some handling for smoothness. First thing I would do to improve the handling, mainly because it's cheaper than new tires, would be to put firmer suspension bushings in the car. I'd probably keep the stock springs if I did that, to keep the ride manageable, and instead look to a tuned set of swaybars down the road to get rid of the rest of the factory understeer.
 

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Wait for the Urethane (sp) bushing kits to come out and then decide.

There are always trade offs and for the street they may not be necessary.

Just a perspective to consider..
 

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I'm hoping for a urethane bushing kit from GM. My ZX2 S/R comes with it standard from Ford Racing. That along with the larger/stiffer suspension parts really make a difference between the ZX2 S/R and the stock ZX2 (.86G instead of .78). Because really if we're already pulling .90G on non-urethane and average suspension parts, I'm betting that "greater then 1G" mentioned in the prodcast isn't too hard to get too. :D
 

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All you racers have your opinions but I have never had any problems with RS-A's for street performance in all weather conditions in almost 10 years of GP GTP's. Granted for the stip or track you want something better but until you get up to the chassis limitations of HP these should do fine. Remember that GM always tunes everything for the middle of the road, balancing performance against controlability by soccer moms (illustrative only, no offense against soccer moms with minivans but really, a gearhead soccer mom would drive a Solstice and deliver the team one at a time :lol: )

What you could consider that would not upset the chassis dynamics too much and would be the perfect way for the driving schools to approach is to substitute 225/60-16 RS/A , the tires from 97-03 GP GTP. Exact same diameter., believe it or not, but 1.1 inches narrower tread. That would allow all four corners to break loose at lower speeds for training purposes and move up to wider tires as a student progresses. Breaking loose earlier would also be conducive to drifting.

Keep in mind as I observed while changing from winter wheels to summer. With a McP strut system there is usually less than .75 inches of clearance between inside of tire and moving suspension parts. Play with the wheels and tires too much and you'll get interference.
 
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