C 20 Tire Size - The 1947 - Present Chevrolet & GMC Truck Message Board Network

muley · 03-14-2014, 05:43 PM

Hola,

I've got a 1969 C 20 Longhorn. The tires on it now are 245/75/16. I'm curious if anyone else runs a bigger size. I've got a 4:10 rear axle and would like to get a little better mileage if I can, but I want to make sure the fronts don't rub on turns.
Thanks if anybody can add to this.

Sicklajoie · 03-14-2014, 06:08 PM

265/75/16 will definitely work.

**jocko** · 03-14-2014, 06:28 PM

Yep, what sicklajoie said. 265/75/16 Same thing I've run on my 72 - no interference, not even close. (the last pic is a member's and I'm almost certain that these are even taller - will try to see what size later on some pics I have on another computer - but I "think" they are 235/85/16s). Still wish I'd bought this old saddle custom camper...

Sicklajoie · 03-14-2014, 06:51 PM

I believe 235/85/16 and 265/75/16 are the same height, just that the 235s are a narrower treadwidth.

**jocko** · 03-14-2014, 07:21 PM

Excellent point, and, you Sir, are correct! I just cross-checked on the BFG site, they are within 0.2" of each other for diameter. So, just depends which aspect ratio you prefer, tall and skinny or a little wider and same diameter.

Sicklajoie · 03-14-2014, 07:28 PM

I went from 235s to 265s on mine. I like the slightly meatier look.

muley · 03-15-2014, 11:18 AM

Thanks for the input! I run 235/85/16 on my Suburban, and like them just fine. My plan is to go as tall as I can to try to gear it up a bit, without interference with the steering or suspension.

Sicklajoie · 03-15-2014, 11:30 AM

What you really need to do is post some pics of your truck!

muley · 03-15-2014, 12:30 PM

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If I figured out how to do this, I'll send more.

muley · 03-15-2014, 12:42 PM

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I need more room than here in the driveway.

Sicklajoie · 03-15-2014, 12:43 PM

Nice!!!

**derotoreut** · 03-15-2014, 10:03 PM

On my '69 C20 I'm running 285/70-17 tires with H2 Hummer wheels on all 4-corners..

1968C20CST · 03-15-2014, 11:14 PM

The hummer wheels look nice.

BlacklandCamper · 03-16-2014, 01:07 AM

Quote:

Originally Posted by derotoreut

On my '69 C20 I'm running 285/70-17 tires with H2 Hummer wheels on all 4-corners..

Quote:

Originally Posted by 1968C20CST

The hummer wheels look nice.

Agreed. Those look awesome.
Is that 2wd? What did you do to get yours level? That is the stance I am looking for.

**derotoreut** · 03-16-2014, 10:34 PM

Quote:

Originally Posted by BlacklandCamper

Agreed. Those look awesome.
Is that 2wd? What did you do to get yours level? That is the stance I am looking for.

It is a 2WD C20. When I did front disc conversion I changed out the front springs. I installed some HD springs (P/N 2772074) bought from NAPA. Tires do not rub at all. They are 285/70-17 tires with H2 Hummer wheels. The ride is a bit stiff, but hey it's a 3/4 ton truck. I never did anything with the rear springs (yet). Here's a comparison of the springs:

The stock HD C20 springs are as follows:

http://www.napaonline.com/Catalog/Ca...752_0162319756

Part No.: 2771752
No. of Coils: 7.92
Free Height: 12.94"
Spring ID: 3.68"
Spring Load Height: 10"
Design Load: 2950
Spring Rate: 1016
Wire Diameter: 0.812"

The springs I put on from C10, C20, C30 from 1973-83. They are as follows:

http://www.napaonline.com/Catalog/Ca...074_0162301536

Part No.: 2772074
No. of Coils: 8
Free Height: 13.61"
Spring ID: 3.676"
Spring Load Height: 10"
Design Load: 3841
Spring Rate: 1060
Wire Diameter: 0.83"

You could also use C30 mid '80's 1-ton springs, but I thought they would be too stiff. Those are:

http://www.napaonline.com/Catalog/Ca...085_0162304063

Part No.: 2773085
No. of Coils: 7.93
Free Height: 13.34"
Spring ID: 3.65"
Spring Load Height: 11"
Design Load: 3289
Spring Rate: 1318
Wire Diameter: 0.906"

Sicklajoie · 03-16-2014, 07:34 AM

I think he put 73-87 springs in the front to level it out.

BlacklandCamper · 03-16-2014, 11:47 AM

I thought that might be the case. I really need to do that to my 71.

BlacklandCamper · 03-16-2014, 11:45 PM

I was thinking along the same lines, but I wouldn't mind a little stiff. The stock spring replacements I list at work are...

Free: 12.94
Installed: 10
Load: 2950
Rate: 1016
Moog part # 6104

The springs I thought of are off of a 1988 R30, there are three versions, standard, with R42 suspension, and R42 HD suspension.
I was going to use the R42 HD option.

Free: 13.59
Installed: 11
Load: 3788
Rate: 1464
Moog part # 6560S

The R42 springs are,

Free: 13.19
Installed: 11
Load: 3289
Rate: 1501
Moog part # 6560

I am looking forward to both seeing how my truck looks leveled out, and driving it. My stock springs are REALLY worn out. The PO already put wedge spacers in them, and they still sag.

/hijack

**derotoreut** · 03-17-2014, 09:07 AM

Keep us posted. I can't wait to hear how it works out for you. Like to see pictures for sure!

72MARIO · 03-18-2014, 01:53 PM

I had 285 75 16 on 16x8 rims and they rubbed the front bottom of the front fender. I have a 3" fabtech lift coil. I swapped them out to 265 75 16. with the bigger tires my ball joints and idler arm hated me. Under 35000 miles and they were toast.

03-14-2014, 05:43 PM	#1
muley Registered User Join Date: Aug 2013 Location: Homedale, Idaho Posts: 160	C 20 Tire Size Hola, I've got a 1969 C 20 Longhorn. The tires on it now are 245/75/16. I'm curious if anyone else runs a bigger size. I've got a 4:10 rear axle and would like to get a little better mileage if I can, but I want to make sure the fronts don't rub on turns. Thanks if anybody can add to this. __________________ Grandpa 1953 M38A1 Jeep 1989 GMC K2500 1958 Alaskan Camper all original WORK : A necessary evil that finances what I really like to do.

03-14-2014, 06:08 PM	#2
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,499	Re: C 20 Tire Size 265/75/16 will definitely work. __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

03-14-2014, 06:28 PM	#3
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: C 20 Tire Size Yep, what sicklajoie said. 265/75/16 Same thing I've run on my 72 - no interference, not even close. (the last pic is a member's and I'm almost certain that these are even taller - will try to see what size later on some pics I have on another computer - but I "think" they are 235/85/16s). Still wish I'd bought this old saddle custom camper... Attached Images

03-14-2014, 06:51 PM	#4
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,499	Re: C 20 Tire Size I believe 235/85/16 and 265/75/16 are the same height, just that the 235s are a narrower treadwidth. __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

03-14-2014, 07:21 PM	#5
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,975	Re: C 20 Tire Size Excellent point, and, you Sir, are correct! I just cross-checked on the BFG site, they are within 0.2" of each other for diameter. So, just depends which aspect ratio you prefer, tall and skinny or a little wider and same diameter.

03-14-2014, 07:28 PM	#6
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,499	Re: C 20 Tire Size I went from 235s to 265s on mine. I like the slightly meatier look. __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

03-15-2014, 11:18 AM	#7
muley Registered User Join Date: Aug 2013 Location: Homedale, Idaho Posts: 160	Re: C 20 Tire Size Thanks for the input! I run 235/85/16 on my Suburban, and like them just fine. My plan is to go as tall as I can to try to gear it up a bit, without interference with the steering or suspension. __________________ Grandpa 1953 M38A1 Jeep 1989 GMC K2500 1958 Alaskan Camper all original WORK : A necessary evil that finances what I really like to do.

03-15-2014, 11:30 AM	#8
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,499	Re: C 20 Tire Size What you really need to do is post some pics of your truck! __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

03-15-2014, 12:30 PM	#9
muley Registered User Join Date: Aug 2013 Location: Homedale, Idaho Posts: 160	Re: C 20 Tire Size If I figured out how to do this, I'll send more. __________________ Grandpa 1953 M38A1 Jeep 1989 GMC K2500 1958 Alaskan Camper all original WORK : A necessary evil that finances what I really like to do.

03-15-2014, 12:42 PM	#10
muley Registered User Join Date: Aug 2013 Location: Homedale, Idaho Posts: 160	Re: C 20 Tire Size I need more room than here in the driveway. __________________ Grandpa 1953 M38A1 Jeep 1989 GMC K2500 1958 Alaskan Camper all original WORK : A necessary evil that finances what I really like to do.

03-15-2014, 12:43 PM	#11
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,499	Re: C 20 Tire Size Nice!!! __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

03-15-2014, 10:03 PM	#12
derotoreut Roto Reuter thats the name... Join Date: Feb 2010 Location: Darien, NY Posts: 1,853	Re: C 20 Tire Size On my '69 C20 I'm running 285/70-17 tires with H2 Hummer wheels on all 4-corners.. Attached Images __________________ ~ Dan My 70 K10 SWB build:http://67-72chevytrucks.com/vboard/s...d.php?t=782232 My 71 SWB build:http://67-72chevytrucks.com/vboard/s...d.php?t=651394 1970 SWB Fleet K10 4X4, 5.3L LM7, 4L60E, Dakota Digital RTX, Vintage Air, Ididit tilt 1971 SWB Fleet C10 - Original SWB Arizona truck, new custom restoration project "Kick out your motor and drive while you're still alive - kick it out!" - Heart 1977

03-15-2014, 11:14 PM	#13
1968C20CST Registered User Join Date: Dec 2013 Location: Norwood, Colorado Posts: 83	Re: C 20 Tire Size The hummer wheels look nice.

03-16-2014, 07:34 AM	#16
Sicklajoie The Niner Join Date: Nov 2010 Location: Broad Brook, CT Posts: 2,499	Re: C 20 Tire Size I think he put 73-87 springs in the front to level it out. __________________ "A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/

03-16-2014, 11:47 AM	#17
BlacklandCamper Registered User Join Date: Sep 2013 Location: Farmersville, TX Posts: 238	Re: C 20 Tire Size I thought that might be the case. I really need to do that to my 71. __________________ Grunt: 1971 C20 Custom Camper. Runs/Drives/Kinda stops. 350Ci, TH350. 4.10:1 D60. Eight Lug LWB is more better. Hell no its not fast! Donkey: 93 Nissan D21, the farm truck. My 1/2 ton SWB. The Indomitable Datsun. 1st BN 3rd MAR. '00-'04



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03-16-2014, 11:45 PM	#18
BlacklandCamper Registered User Join Date: Sep 2013 Location: Farmersville, TX Posts: 238	Re: C 20 Tire Size I was thinking along the same lines, but I wouldn't mind a little stiff. The stock spring replacements I list at work are... Free: 12.94 Installed: 10 Load: 2950 Rate: 1016 Moog part # 6104 The springs I thought of are off of a 1988 R30, there are three versions, standard, with R42 suspension, and R42 HD suspension. I was going to use the R42 HD option. Free: 13.59 Installed: 11 Load: 3788 Rate: 1464 Moog part # 6560S The R42 springs are, Free: 13.19 Installed: 11 Load: 3289 Rate: 1501 Moog part # 6560 I am looking forward to both seeing how my truck looks leveled out, and driving it. My stock springs are REALLY worn out. The PO already put wedge spacers in them, and they still sag. /hijack __________________ Grunt: 1971 C20 Custom Camper. Runs/Drives/Kinda stops. 350Ci, TH350. 4.10:1 D60. Eight Lug LWB is more better. Hell no its not fast! Donkey: 93 Nissan D21, the farm truck. My 1/2 ton SWB. The Indomitable Datsun. 1st BN 3rd MAR. '00-'04 Last edited by BlacklandCamper; 03-16-2014 at 11:55 PM.

03-17-2014, 09:07 AM	#19
derotoreut Roto Reuter thats the name... Join Date: Feb 2010 Location: Darien, NY Posts: 1,853	Re: C 20 Tire Size Keep us posted. I can't wait to hear how it works out for you. Like to see pictures for sure! __________________ ~ Dan My 70 K10 SWB build:http://67-72chevytrucks.com/vboard/s...d.php?t=782232 My 71 SWB build:http://67-72chevytrucks.com/vboard/s...d.php?t=651394 1970 SWB Fleet K10 4X4, 5.3L LM7, 4L60E, Dakota Digital RTX, Vintage Air, Ididit tilt 1971 SWB Fleet C10 - Original SWB Arizona truck, new custom restoration project "Kick out your motor and drive while you're still alive - kick it out!" - Heart 1977

03-18-2014, 01:53 PM	#20
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,051	Re: C 20 Tire Size I had 285 75 16 on 16x8 rims and they rubbed the front bottom of the front fender. I have a 3" fabtech lift coil. I swapped them out to 265 75 16. with the bigger tires my ball joints and idler arm hated me. Under 35000 miles and they were toast. __________________ 1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD

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