Tire Sizes

Does anyone know what exactly the tire measuerments mean?

I know like a 225/40/18 is 225 wide 40 hieght off rim and 18 is inner circumfrance but 40...how is that measured! I want really low pro tires on my rims but im not sure how low I can go...also whats the widest I can go on an alero...ive heard 255 is the widest! What is the best for the car?

here's the lowest you can go.
http://invision.aleromod.com/index.php?sho...c=12596&hl=tire

For faster answers use the search function, this question comes up at least twice a month. theres a lot of info on the site.

thanks I appreciate it...perhaps a bit too little tire for me!

[AlbinoMonkeyRat]

I'll help you out. I'll use my tire size for the example: 225/50/16

225 is the width of the tread in mm
50 is the percent of the tread's measurement and measures the wall (so my wall is 112.5mm)
16 is (well obviously) the diameter in inches of the wheel that the tire fits.

this link should help you out when your buying new wheels and the tires that match.
http://www.miata.net/garage/tirecalc.html