Heres an example say you have a tire and rim all together. 245/75 R19.5

The width of this tire measured in milliliters is 245. It is measured from sidewall to sidewall.

The 75 number is actually intended as the height of the tire from the bead to the top of the tread. Better known as the aspect ratio it is calculated as 75% of the tire width, which in this case is 245 so, .75 * 245 = 183.75mm. That is the height of the tire. If this setup was 245/65 R19.5 then it would be 65% of the tire width.

The R stands for the tire construction, which in this case is Radial.

19.5 stands for the rims width in inches.

Hope this helps :)

The width of this tire measured in milliliters is 245. It is measured from sidewall to sidewall.

The 75 number is actually intended as the height of the tire from the bead to the top of the tread. Better known as the aspect ratio it is calculated as 75% of the tire width, which in this case is 245 so, .75 * 245 = 183.75mm. That is the height of the tire. If this setup was 245/65 R19.5 then it would be 65% of the tire width.

The R stands for the tire construction, which in this case is Radial.

19.5 stands for the rims width in inches.

Hope this helps :)