Sorry Padgett, gotta big time disagree with you. I'll bet you a lunch that 18" are standard. They showed P245/45R18 tires at the Detroit Autoshow, and stated over and over that this is the car you can buy for "around" $20,000. I asked about wheels and tires and they said: "This is the production car, that's the size wheels that will be on it.."

Granted, that is just the showperson, but there's article after article out there emphasizing the 18's as a feature. It will have 18 inch P245 wheels and tires standard - they would be crazy not to after all this harping on it.

As far as peak cornering, I respectfully think your statement is oversimplification. There's plenty of data that shows a 245 wide tire is or can be a very appropriate size for great cornering. The new honda s2000 rear tire is exactly a 245 wide tire. Z4 is running with a 225/255 split (at curb a little heavier than Solstice). The extension of your statement is that heavier loaded tires corner better - this is obviously not the case. If it was, than the corvette would still be running around on 185 tires (max load for the width, right?)

[TIRE LESSON FOR THOSE WHO CAN'T SLEEP:]

Peak cornering is highly dependent on distribution of footprint pressure, and the wider the tire the lower the footprint pressure.

Also, the lower the load on the tire, the lower the footprint pressure.

Both of these will generally increase peak lateral traction.

What does tend to happen is the "edge" or peak lateral force gets "peakier", meaning that if the tire doens't have enough sidewall give to allow deflection and redistribution of normal force through the tirepatch, the car gets less controllable at the peak lateral traction. This is all carefully balanced (hopefully) when the tire is "tuned" by the guys who develop ride and handling.

Also playing into the equation, probably as big if not bigger a factor, is the tread compound used (assuming you have a decent hi-perf tread pattern). A good all 'round compound will have a different mix of characteristics, grippier compounds tend to generate heat which (on road racing applications) increased pressure, which increases footprint pressure (if you started at optimal pressure) which leads to cornering fade as the race goes on.... you get the picture.

This isn't as much a factor on autox (heat generation), and one easy way to get around non-optimal tire grip is to work with a tire pressure and camber setting that generates the right amount of grip. Problem is you only get four runs to tune this in, so it helps if you've figured out a decent setting to start with...

[/TIRE LESSON FOR THOSE WHO CAN'T SLEEP:]

You can have too much tire, sometimes, but at 2800 lbs or even 2900 lbs (curb) I don't think the Solsice is in danger of being there.

Max lat will tell some of the picture, but haven't seen anywhere that information on the solstice exists (at least not yet).

18's are a little big (and heavy) for this car, but looks sell cars, so what can you do?

-solsticeman