What do the tire numbers mean and what should I up grade to?

[Chrisz24]

On my 98 I have the 5 spoke cast alumnium wheels (16 in) that came standard on the Z28, the tires are stock P235/55R-16 touring is what the paper said, what does all this mean? all I know is the 16 stands for 16".
I need to replace 2 because they dont look that good but the other 2 on the rear look good so I am keeping them for now, what should I look for?
I like the look of the Z28 tires I see from the chevy book it says they are P245/50ZR, I know the Z means high speed.
I dont want to spend a lot of money but at the same time I would like to have something that handles better in the rain and snow and has better cornoring + looks more agressive. I dotn care if it has a Z rating since I dont go over 90
Sorry this is so long I just dont want to regrette buying the wrong thing.
Chris

[99Camaro99]

I upgraded to 245/50/R16s and am happy. From the back the tires look nice and large. It's agressive looking. I have heard that you can go up to 275s but that's just going to cost you more and since you said "I don't drive over 90," I'm assuming you don't race much. You really won't need that extra thread. As for the #s. 245/50/R16. The 245 is the diameter of the tire in millimeters the 50 is the aspect ratio on the tire R is the rating and 16 in the size of the tire. Hope this helps.

[Ak74]

Ok, I'm going to use your (and my) tires as an example: P235/55R-16, the "P" means its a passenger car tire (LT would mean light truck). 235 is the width (in millimeters, multiply by .04 to convert millimetes to inches). 55 is the aspect ratio, thats how much sidewall your tires have in comparison to their width. R means its a radial tire. 16 is the diameter of the wheel. ---- Now, to determine the diameter of your tires you multiply the width (235), by .03943, by the aspect ratio (55%), by 2 (you have to include sidewall width twice), then add the wheel diameter (16).

The equation looks like this:

235 x .03943 x .55 x 2 + 16.

The reason I bring this up is because you can use 235 x .03943 x .55 to determine the sidewall width and compare different size tire/wheel combos...Hope this helps.