Ok, here is what the lowdown on tires is:

The first number is the width of the tread in millimeters. The second number is the percent of the first number that the sidewall's height is. The third is the diameter of the wheel.

So...

215/50/15

Tread is 215mm wide

Sidewall is 50% as high as the tire is wide... 107.5mm (that might be the height of both added together)

Personally, I would go with the 215/55/15's. They won't give you too harsh of a ride, and yet they will be a vast increase in performance (and looks). Definately go for some high or extreme performance tires... The Dunlop Sp8000 is really good, also the Nitto NT450 (I have friends who have these tires and love them), Kumho also makes some good tires, but I haven't had any experience with them. Keep in mind that upgrading to tires of this nature will be more costly, but it is an investment in safety, because you will be able to stop faster, and have better grip for maneuvering etc...Sticking with the 15's is actually a good choice for performance, because you have less unsprung weight.

A 780 is not a super hi-po handling machine - it's a luxury-biased coupe with balls. The 15" alloys (I agree with the other poster - they should be 7" wide) are plenty adequate for 205/60s or 250/55s. If I remember right, 205/60 was the stock size on the 780 Turbo, 195/65 was stock for the V6 780. The 205s will give you all the grip you could want in a 780, respectable handling and a comfortable ride. Sticking with the 15" size is not really a drawback unless you want to squeeze out that last 0.03g of cornering that only 17" wheels can give.

Drawbacks of larger wheels :

- usually increased rotational mass (i.e. slower acceleration).

- usually more unsprung weight.

- easier to damage on bad roads/curb shots.

- wider/lower profile tires are noiser and harsher-riding.

- wider tires hydroplane easier.

- wider/lower profile tires provide a little extra grip, but are sometimes tricky at the handling limits (i.e. when they break loose, they do so suddenly and dramatically.)

- more $$$ at purchase time and usually more frequent tire replacement intervals.

Those 15" cross-spoke wheels are some of the best looking rims Volvo ever made anyway.

The 780 is an excellent Grand Tourer, so that's what I would emphasise. Of course, this is just my opinion, what I would do if I had a 780. If you were talking about a 740 Turbo w/M46, then maybe 17" wheels, ipd bars, lowered, extra boost...

KC,

Hmmm...ok, well u said u have the "stock mesh wheels". Im guessing that u ment those rims w/ the "diamond" spokes. I believe those rims are 15x7" rims. So Im wondering why the previous owner had 185/65-15. Thats a little narrow for those. Im pretty sure the stock size was 205/60-15. I think that a 205/ or 215/ widths would be fine. I would probably put on 205/55-15 on those personally cuz the sidewall is shorter so it would give u less flex from side to side on the sidewalls.

How wide are the wheels? 6"? I'm currently using 205/55/15 on my 240, and it gives a pretty good ride, but also better handling because of the much shorter sidewall than my previous 185/70/14 tires. I would guess that the stock tire size on your car was 195/60/15, in which case 205/60/15 would be a bit taller, and 205/55/15 would be a tiny bit shorter. Assuming the wheels are 6" wide, I would use either 205/55/15 or 205/60/15.

Concerning brand, it really depends on what you want from your tires (wet, dry, noise, tread life, etc), but take a look at Dunlop, Bridgestone, Kuhmo, and Yokohama if you want performance tires that aren't too expensive. Definitely check out www.tirerack.com for specs, sizes, prices, and especially the customer feedback for most brands available.

Good luck.

OK. First thing you have to realize is what the tire symbol stands for. The first number (Eg 185) stands for the tire width, while the 2nd (65) stands for the percent showing in the sidewall (or something like that). The third stands for the radius of the wheel. The opinion of what to switch too just depends on what you want to run. I personally stay stock with the stock rims, if thats what Volvo wants, thats what Volvo gets. Personally I'm looking to move up to 17" rims, but thats gonna cost a pretty penny. If you want more info on the different rim sizes exe., check http://www.mcbrooms.com/volvo/tires.htm for a complete listing. Hope this helps!