tire size

[bigmac#11]

not sure how to read what my actual tire size is any help would be appreciated

[Reddawg454]

18x8.5-8 Means 18" tall, 8.5" wide on an 8" rim

[JohnnieB]

The numbers embossed on the sidewalls are only approximate and the height may be off by an inch or more in either direction.
The tire width is closer to actual and rim size is mighty close.

As mentioned, the first number indicates the tire diameter (height), but my tires have exactly the same numbers and are only 17" tall.

Making matter worse, the MTD (Mounted Tire Diameter) given on the manufacturer's website is 18.3", which is even further for the actual height than the numbers on their sidewall.

The only way to find out how tall your tires are is to measure them.

Using a yardstick and level is usually close enough, but to get the effective tire height under actual driving conditions, measure how far the cart travels per tire revolution and divide by Pi.

There is only room for four complete tire revolutions on the sidewalk between my house and garage, so I measured the distance of travel with me driving cart for four revolutions (214.125"), divided by 4 and then divided by 3.14159265358979 to get a dynamic diameter of 17.0395260947761"

[yurtle]

You can also place a chalk mark on the tire, and measure the starting and ending point. I'd go several revolutions for more precision. This is useful if you have a speedometer.