numbers on the tires?

[cookbob]

im gonna buy some new decent 15 inch rims soon and the rubber on them is 195 65 R15 and i was wonderin wat the 1st two numbers mean. also if the tires arent the same size as my factory ones will it mess up my rpms and speedo?

[cookbob]

they might have been 195 60 R15 but i cant remmeber

[EK 2.0]

the 195 is the width of the tires in mm's and the 60 or 65 is the aspect ratio...basically, 60 percent of 195 is the height of the tires...

You can go with bigger rims and a lower aspect ratio...for example...

a 195 55 16 or a 205 50 16 depends on your budget and what you ultimately wanna go for...

[Ferio_vti]

here yah go:
http://auto.howstuffworks.com/tire2.htm