Stock tire diameter?

[raunch]

Trying to figure my corrected mpg's with 33" tires vs. the stock tire diameter that the speedometer/odometer was set up for: 33"/stock D = correction factor for actual miles traveled.
Thanks.

[Colorado Kid]

You give us very little info about your rig to go on, so here is my SWAG.
First Assumption: Your '83 Suburban is a K1500
Second Assumption: It came with P235/75R15 Tires (The lable on the door post will tell you what size it came with.)

235 = section width in mm, = 9.25 inches
75 => 0.75 aspect ratio (ar = section width/sidewall height)
sidewall height = 0.75 x 9.25" = 6.94"
diameter = (2 x sidewall height) + rim diameter = (2 x 6.94) + 15 = 28.9"

Since you don't really know the diameter of your "33s" down to the tenth of an inch just use 33/29 for your correction.

That is:
(33/29) x odometer miles = actual miles.
(29/33) x indicated speed = actual speed.

I think I left enough bread crumbs that you can follow the trail even if your stock tires were a different size.

[JohnC]

(33/29) x indicated speed = actual speed.

[raunch]

Sorry for the slim details--trying to slip TDP time in here at work. With the info given, I'll be able to figure it out. Thanks.
BTW, the suburban is a K2500 with a TH400. Figured without a factor, MPG's are about 15, at 60 MPH. With a correction factor of 1.13 (33/29), that puts the actual MPG's at 16.95. As soon as I can make it happen, I'd like to swap in 700r4 and get even better MPG's--but that's another thread altogether.
Thanks again.