Rear tire 20inch fitment ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kens65fb · 12-21-2022, 04:13 PM

Will a 275/40/20 tire fit the rear of my fleetside, it has been lowered 4 inches

4.75 inch backspace

28.7 inch diameter,

If not, what is a good size for a 20 inch wheel in the rear.

**cwcarpenter98** · 12-21-2022, 08:56 PM

Stock 12 bolt or slightly wider axle from a later year truck?

kens65fb · 12-22-2022, 08:44 AM

Quote:

Originally Posted by cwcarpenter98

Stock 12 bolt or slightly wider axle from a later year truck?

Stock 12 bolt rear

Currently using 275/60/15 on the rear, they are tight, but don rub.

SCOTI · 12-22-2022, 10:30 AM

There's never an exact answer for these questions. What fits on 5 different trucks might have issues on 5 other trucks because of subtle variances. What's the BS on the 15's?

If the wheels are the same width & BS, only the height is slightly different. At only 4" of rear drop, that change shouldn't be an issue.

There can be minor size variances between similar section width tires (275mm), especially when using different diameter combos w/different aspect ratios (40 vs 60).
It comes down to where the new combo will sit relative to where the old was & the amount of clearance the old combo has.

kens65fb · 12-24-2022, 10:11 AM

Quote:

Originally Posted by SCOTI

There's never an exact answer for these questions. What fits on 5 different trucks might have issues on 5 other trucks because of subtle variances. What's the BS on the 15's?

If the wheels are the same width & BS, only the height is slightly different. At only 4" of rear drop, that change shouldn't be an issue.

There can be minor size variances between similar section width tires (275mm), especially when using different diameter combos w/different aspect ratios (40 vs 60).
It comes down to where the new combo will sit relative to where the old was & the amount of clearance the old combo has.

Will a 29 inch tall tire be too much?

SCOTI · 12-24-2022, 01:14 PM

Quote:

Originally Posted by kens65fb

Will a 29 inch tall tire be too much?

It shouldn't @ only 4" of drop.

To 100% verify, set the truck up w/some jack stands so the rear end is compressed/has weight on it but off the ground. Tape some 2x4 blocks to the tire/s, spin the wheels/tires & see what happens.

**Corts60** · 01-01-2023, 09:05 AM

I use this tire calculator quite a bit when trying to decide on wheels/tires. It’s nice because you can enter your existing tire size and then compare to the new one. Just an idea to help you out.

https://tiresize.com/comparison/

12-21-2022, 04:13 PM	#1
kens65fb Registered User Join Date: Dec 2018 Location: Dallas, PA Posts: 551	Rear tire 20inch fitment ? Will a 275/40/20 tire fit the rear of my fleetside, it has been lowered 4 inches 4.75 inch backspace 28.7 inch diameter, If not, what is a good size for a 20 inch wheel in the rear. Last edited by kens65fb; 12-21-2022 at 05:31 PM.

12-21-2022, 08:56 PM	#2
cwcarpenter98 Senior Member Join Date: Jan 2018 Location: Hickory Flat, GA Posts: 4,491	Re: Rear tire 20inch fitment ? Stock 12 bolt or slightly wider axle from a later year truck? __________________ Christian Carpenter 1963 C10 - Frankentruck 283, Muncie 3 speed with overdrive Overdrive wiring here 1963-ish truck bed trailer - Half-Wit 1981 C10 - Penny 305, th350 --> Soon to be 350, Saginaw 4 speed 1995 Dodge Dakota Sport "I'll put it simple: if you're going hard enough left, you'll find yourself turning right." - Doc Hudson

12-22-2022, 10:30 AM	#4
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 22,066	Re: Rear tire 20inch fitment ? There's never an exact answer for these questions. What fits on 5 different trucks might have issues on 5 other trucks because of subtle variances. What's the BS on the 15's? If the wheels are the same width & BS, only the height is slightly different. At only 4" of rear drop, that change shouldn't be an issue. There can be minor size variances between similar section width tires (275mm), especially when using different diameter combos w/different aspect ratios (40 vs 60). It comes down to where the new combo will sit relative to where the old was & the amount of clearance the old combo has. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

01-01-2023, 09:05 AM	#7
Corts60 Just here to tinker Join Date: Jun 2008 Location: Holland, MI Posts: 3,697	Re: Rear tire 20inch fitment ? I use this tire calculator quite a bit when trying to decide on wheels/tires. It’s nice because you can enter your existing tire size and then compare to the new one. Just an idea to help you out. https://tiresize.com/comparison/ __________________ 78 C10 SWB Diesel #1 (wrecked)http://67-72chevytrucks.com/vboard/s...1978+silverado 78 C10 SWB Diesel #2 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=650751 60 GMC Suburban (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=445526 60 GMC 1000 (sold)http://67-72chevytrucks.com/vboard/showthread.php?t=298235 67 GMC 1500 (sold) http://67-72chevytrucks.com/vboard/s...d.php?t=803695 73 Chevy C20(Daily)http://67-72chevytrucks.com/vboard/s...d.php?t=852767 86 Suburban(summer unit) http://67-72chevytrucks.com/vboard/s...d.php?t=810697 88 Suburban 4x4(sold)



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