Alright so i've noticed a lot of tire questions on here, such as size, speed ratings, and what will fit where,

For fitment on a vehicle, with no other mods done to the car, the best place to look is on www.bigwheels.net,
this site will give you specs such as stock rim, maximum size fitment (without mod) offset range, bolt pattern, and oem fitment.
So chech that site out if your looking for the biggest rims you can do without modding.

As for tire size, and this is real newbish, but it breaks down real simple. For example:

195/70R14


The first number 195 represents the cross section width of the tire in millimeters.

Second number 70, is an aspect ratio or percentage which represents the height of the tire in comparison to it's width, so this tire
is 70% tall as it is wide.

The R simply stand for Radial construction

And the final number 14 means it has a 14 inch rim diameter.

Tip for rims and Speedo being off,,,

now say you put on a set of 17's and your moving up from your 14's, my best advice that is least confusing is to find out the overall diameter of the orignall factory tire, and compare that to tire sizes that will fit your rim. For example my 2005 Cavalier came with 195/70R14 Goodyear Conquests,, thier overall diameter is 24.8". Now I just ordered a set of rims for next spring, 17"x8.00 Boss wheels, and to determine my the tire size that will be best fitment i look at tires offered in a 17, and than check for overall diameter of the tire in different sizes, and also what rims sizes they fit on, for instance a 245/45R17 Eagle Featuring Response Technology has an overall diamet of 24.9" and will fit a 7.00'' to 8.00" rim(in width) So my new tires would be .1" taller than stock, not much difference on the speedo.

Another sizing technique, called plus fitment, also come in handy if you want wider,, if you wish to increase width the first number must be larger, yet to remain in height to the oem fitment so the speedo doesnt get screwed the second number must be decreased. The rule is 10 to 5, for every 10 mm you increase the width ( 195, 205, 215) the second number must be decreased by 5 (70, 65, 60). This only works thought if your comparing the number on one rim diameter. So a 195/70R14 it skinnier but just as tall as a 215/65R14

I hope this helps a bit and feel free to correct me cause i most likely said something wrong