Question on 18" tire SIZE?

[99gatorbird]

I just won a set of 18" Z06 wheels they are 18X9.5 . I am being a cheap A$$ about tires. I want to go with a 245/40ZR18 by Kumho Ecsta Supra 712, out the door road hazard and lifetime balance and rotate is 655. My buddy says that 245's are to skinny for 9.5 inches. The tire guide said that 245's WILL fit a 9.5" rim. he thinks i should 275/35's which are about 200 dollars more. I am trying to get a good set of tires for a low price. My buddy says try to get those yokohama AVS dB S2 which are about 30 more dollars a tire but have a tread wear rating of 320 vs the Kumho's @ 280. Does that much tread wear rating matter. I have been to tires.com and tirerack.com. Tirerack offers road hazzard but charges shipping. Tires.com offers no road hazzard and NO shipping. Lose Lose situation. The 655 i quoted was a local joint here in town. So Help me out as much as Y'all can, Thanks [img]graemlins/burnout.gif[/img] [img]graemlins/burnout.gif[/img]

[fenderman]

Let's deal with tire size first. The 245 in the size stands for the width in mm. 245 translates to 9.6 inches wide. 275 translates to 10.8 inches wide.

The second number is an aspect ratio measured in percentage. A tire having a number XXX/65 would have a height equal to 65% of XXX. So a 245/40 would have a distance of 245 * .40 = 98mm or 3.86 inches between the bead of the tire and the top of the tread. A 275/35 will have a distance of 3.79 inches between the bead and the tread. Total tire height will be roughly 26 inches for both sizes from the ground to the top of the tire. ([3.8*2]+18)

I know this from working in a car garage for roughly 3 years of my college career, but just in case-

Source for verification of above statement: http://www.tirerack.com/tires/tiretech/general/size.htm

I cannot help you with tread wear ratings, but I don't think that small of a difference in numbers matters much. Hope this helps a little bit. Maybe someone will chime in on the tread wear ratings with more sound information than I was able to provide.

[ August 19, 2003: Message edited by: fenderman ]</p>

[99gatorbird]

THANKS MAN U KNOW YOU STUFF. i FOUND THIS WEBSITE HELPFUL TOO ABOUT TIRE DIAMTER. http://www.binaryinc.org/modules.php?name=Auto_Calc