tire diamater
 

What is the diamater of a 245/70R19.5?

I could be wrong. But that sounds like a 30 inch tire. I think they come on the low-pro trucks like internationals with the small wheels. But that is a guess

its 33" tall by 9.65" wide.

245 mm width x 0.70 aspect ratio = 171.5mm sidewall height = 6.75 inch.

6.75 + 6.75 + 19.5 = 33 inches.


Rusty

here is a web site that helps with finding the diameter of a tire and also weather or not a new tire will fit with the spaceing.
http://members.aol.com/agspeed/tiresize.htm

Interesting website, but it ignores a vital measurement when determining if a new wheel will fit. Backspacing. If backspacing or set back as it's somtimes called is radically different, either inward or outward, interference might occur.