Tire Diameter or Size Question 72 GMC 4x4 (stock) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hdflstf · 10-30-2008, 09:46 PM

I'm looking for what the original equipment tire diameter was on a 72 GMC 3/4T 4x4. I need to do some math to figure out how far off the speedometer is but I need to get the starting point...

TIA

**Stocker** · 10-30-2008, 10:15 PM

May have been optional sizes... Should be the same as my '72 K20, though. It came with 7.50-16s, about 31.8" tall iirc. Armstrong Norsemans (traction) in that size were 32.2", again if my memory is correct.

A bit of searching indicates 265/75-16 may be close to the same diameter as the OEM bias-ply tires.

If you don't have them already, here's a couple of calculators:
http://www.discounttire.com/dtcs/infoTireMath.dos
http://www.miata.net/garage/tirecalc.html

hdflstf · 10-30-2008, 11:56 PM

Thanks. That gets me a start on how much my speedo is off.

10-30-2008, 09:46 PM	#1
hdflstf Registered User Join Date: Oct 2007 Location: Desert Southwest Posts: 540	Tire Diameter or Size Question 72 GMC 4x4 (stock) I'm looking for what the original equipment tire diameter was on a 72 GMC 3/4T 4x4. I need to do some math to figure out how far off the speedometer is but I need to get the starting point... TIA

10-30-2008, 10:15 PM	#2
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,722	Re: Tire Diameter or Size Question 72 GMC 4x4 (stock) May have been optional sizes... Should be the same as my '72 K20, though. It came with 7.50-16s, about 31.8" tall iirc. Armstrong Norsemans (traction) in that size were 32.2", again if my memory is correct. A bit of searching indicates 265/75-16 may be close to the same diameter as the OEM bias-ply tires. If you don't have them already, here's a couple of calculators: http://www.discounttire.com/dtcs/infoTireMath.dos http://www.miata.net/garage/tirecalc.html __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay Last edited by Stocker; 10-30-2008 at 10:28 PM.

10-30-2008, 11:56 PM	#3
hdflstf Registered User Join Date: Oct 2007 Location: Desert Southwest Posts: 540	Re: Tire Diameter or Size Question 72 GMC 4x4 (stock) Thanks. That gets me a start on how much my speedo is off.



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