How many miles are those rated for?

Tires are 80,000 miles w/ proper care

I wouldnt suggest getting anything other than the stock size with any 16x7 rim for 2 reasons...one is availability if you go with a 235/55/16 tire you have very little in the way of an H or V/Z rated tire to choose from like 2-3 options depending on which way you wanna go (not the greatest options in the world either) you could get a traction t/a BFG but those only come in a T rated so are not a true performance tire. The 245/50/16 would be youre other option which is a good tire size but youre rim is slightly too narrow for the tire to wear properly, you ever seen when the center wears out before the rest of the tire? Thats what will happen (especially on youre front tires if you drive like me ) That leaves youre stock size 225/60/16 plenty of options for performance tires and no problems with clearance or wear (again unless you drive like me ) one great option for all season driving is the BFG Traction T/A which you can get in either the H or V rating and another good option if you have a dedicated set of snow tires is the Kumho KH11 (like I have on mine) it comes in a W rating and is a really low priced and STICKY!!!!!! tire with great water traction....just dont try to drive them in the snow!

for reference the old saying "speed rating" is really incorrect the tires ability to corner and handle better at speed is also increased with the higher speed rating

I have learned to get away from calling it a speed rating and have started to call it a performance rating which is really more accurate.
but is we are talking speed here goes

*=112 mph
T=118 mph
H=130 mph
V=146 mph
Z=146+ mph

under the Z rating is W rating which is 168 mph and Y rating which is 189 mph

wont likely have many people here NEEDING more than a W rating for safety reasons

Sorry to ramle on so much about tires BUT it is my business

I didn't mind dropping down a "performance rating" with my tires. I mean, seriously, how often are you driving 100+ mph for extended periods of time?

Tires with a higher speed rating are stronger then the ones with lower ratings. Just for that fact I try to get nothing low. Helps out when running over rocks, and curbs also.

Last I checked, you probably shouldn't be doing that sort of driving in a Bonneville anyway

Actually with an SE model Bonne they just took an * or T rated tire, but again it has alot less to do with top speed than it does to do with handling....think about all the sweet handling cars with Z rated tires that have top speeds no where near 160+ mph

Examples
BMW 3 Series (yes M3s CAN go 155 but a standard 325i handles EXCELLENT and has a top speed no where near 160)
Acura integra Type R
Mazdaspeed Protege
Mazda Miata
Civic Si

That'* true, but it isn't only the tires that make them handle like they do. The suspension components and design are a lot different on some of those cars than that of the bonneville. Those are sports cars, the bonneville is a touring sedan.

True dat...however the W rated Kuhmos on my SSEi make it handle a world better than the T rated Pirellis it had on it when I got it. They are the same width and profile as your Traction TAs but I would bet if we measured skidpad numbers the Kumhos would bite better....however in the real world snow on mid Missouri your Tractions would bite and grab through the white flaky stuff alot better.....My point is if you have a dedicated set of snow/winter tires you should definatly go with a Z rated tire. My Bonne however will sit this winter out, while I drive my Buick (again which has a dedicated set of snow tires, or all season tires at that)

I'm a little confused why a wider tire is worse for winter. It would seem that a wider contact patch would provide better traction no matter what the conditions. I wouldn't think a 4000 lb. car would have any trouble getting winter traction with 235s. Isn't that the logic behind an off-roading tire or a float tire? Can someone explain the physics of this to me?