Tire and Wheel Size Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rnd · 04-30-2013, 06:08 PM

I recently purchased a 1977 GMC C2500 3+3 no duals. It has front disc brakes(factory) and a 14 bolt floating axle with 4:10 ratio. 454 with 400 auto trans.

My question(s) is/are: What bolt pattern does it have? 8x165.1 /8x6.5 or 8x170? or something else.

It has 33/12.5/16.5 on it now with factory wheels. Stock was 9.50/16.5.

I think I would like to put on 275/60R18's or 265/50R20's.

I can't order online without knowing the bolt pattern..

Any thoughts and/or info would be appreciated.

Thank you, Randy

P.S. How about offset?? Is this something I need to be concerned with ?

b454rat · 04-30-2013, 06:16 PM

8x6.5. The tires you listed are kinda small, is this 2wd or 4wd. By the C in 2500 guessing a 2wd. I have 305/55/20s on my 'Yota, and they are equal to a 33x12.5....

Rnd · 04-30-2013, 06:25 PM

Quote:

Originally Posted by b454rat

8x6.5. The tires you listed are kinda small, is this 2wd or 4wd. By the C in 2500 guessing a 2wd. I have 305/55/20s on my 'Yota, and they are equal to a 33x12.5....

Yes, it's a 2 wheel drive. The 33 x12.5 seem a bit tall I would like to get around the 31x10.5 range.

I'm having a hard time finding the running diameter of a 9.50 x 16.5 tire.

If I could come up with this it would help me in tire and wheel selection.

Thanks for the input.
Randy

Ziegelsteinfaust · 04-30-2013, 07:07 PM

A 265/70/16 is the same size, and offers lots with the E load rating. If your willing to go smaller.

b454rat · 04-30-2013, 07:09 PM

These trucks came stock with 235/85/16s, which is about a 31-32" tire. The 9.5/16.5 is roughly the same size I think....maybe tad shorter and wider...

If you want a wider tire, but roughly the same height, a 275/70/16 is close. If you want wider, then need a 60 series tire...

**MusicMan70** · 04-30-2013, 10:52 PM

Quote:

Rnd
I'm having a hard time finding the running diameter of a 9.50 x 16.5 tire.

If I could come up with this it would help me in tire and wheel selection.

I measured 29.5" on the truck.

Rnd · 05-01-2013, 12:35 AM

Thanks guys that helped.

At this point I think I'm going to get a set of Mickey Thompson Classic 3's. 17x9x8.65 with Pirelli Scorpion STR 265/65/R17

That should be around the stock diameter and slightly wider.

04-30-2013, 06:08 PM	#1
Rnd Registered User Join Date: Apr 2013 Location: erie Pa Posts: 34	Tire and Wheel Size Question I recently purchased a 1977 GMC C2500 3+3 no duals. It has front disc brakes(factory) and a 14 bolt floating axle with 4:10 ratio. 454 with 400 auto trans. My question(s) is/are: What bolt pattern does it have? 8x165.1 /8x6.5 or 8x170? or something else. It has 33/12.5/16.5 on it now with factory wheels. Stock was 9.50/16.5. I think I would like to put on 275/60R18's or 265/50R20's. I can't order online without knowing the bolt pattern.. Any thoughts and/or info would be appreciated. Thank you, Randy P.S. How about offset?? Is this something I need to be concerned with ? Last edited by Rnd; 04-30-2013 at 06:13 PM.

04-30-2013, 06:16 PM	#2
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,469	Re: Tire and Wheel Size Question 8x6.5. The tires you listed are kinda small, is this 2wd or 4wd. By the C in 2500 guessing a 2wd. I have 305/55/20s on my 'Yota, and they are equal to a 33x12.5.... __________________ 2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 4” SAS 1999 GMC Yukon 350/4L60 6" SAS

04-30-2013, 07:07 PM	#4
Ziegelsteinfaust Registered User Join Date: Dec 2012 Location: Temple City Posts: 3,666	Re: Tire and Wheel Size Question A 265/70/16 is the same size, and offers lots with the E load rating. If your willing to go smaller.

04-30-2013, 07:09 PM	#5
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,469	Re: Tire and Wheel Size Question These trucks came stock with 235/85/16s, which is about a 31-32" tire. The 9.5/16.5 is roughly the same size I think....maybe tad shorter and wider... If you want a wider tire, but roughly the same height, a 275/70/16 is close. If you want wider, then need a 60 series tire... __________________ 2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 4” SAS 1999 GMC Yukon 350/4L60 6" SAS

05-01-2013, 12:35 AM	#7
Rnd Registered User Join Date: Apr 2013 Location: erie Pa Posts: 34	Re: Tire and Wheel Size Question Thanks guys that helped. At this point I think I'm going to get a set of Mickey Thompson Classic 3's. 17x9x8.65 with Pirelli Scorpion STR 265/65/R17 That should be around the stock diameter and slightly wider.



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