'85 C10 tire fit/stuff question (not the normal questions you're used to seeing here)

[1x1_Speed_Craig]

A quick background before asking my question...

I came from 20 years in the Jeep world, and have always loved low-COG builds with minimal-to-no-lift and big tires. It drives me a little nuts to see vehicles lifted higher than they need to be for a given tire size (I see it daily here in East Tennessee, and online everywhere).


A couple of my previous low-COG builds.

Rare military '86 Jeep CJ-10a converted to 4WD, and running 34 x 9.50 "pizza cutter" Swampers on stock-height front springs and no body lift. Wheels are narrow (5.5"?) Toyota steelies from an '80s-era 4-Runner, IIRC.

You must be registered for see images attach

'05 LJ on 1-ton axles, H2 whees with 37" x 12.5" tires and a minimal 3.5" lift. Axle width, wheel/tire sizing, and the AEV highline body kit all helped clear this wheel/tire combination; the flex & tire stuff was amazing. When I was working on this project, people were typically lifting these Jeeps 4.5" to clear much smaller 33" tires, just for some comparative perspective.

You must be registered for see images attach

And back to current day, here's my other daily-driver CUCV, an '86 M1008 on sagged OEM front springs, H2 wheels with ~5 5/8" backspacing. They clear the 55/80R-17 (33" x 10") tires beautifully.

You must be registered for see images attach

So...now my question.

I'm slowly working on this mutt '85 CUCV/C10 project. Here it is sitting on its "new" '86 GMC C15/C10 chassis and "roller" GMT wheels & tires (these will be replaced).

You must be registered for see images attach

Unlike a good portion of the 2WD crowd here, I do not want to lower the truck, unless it's just a little in the back to level things out with the front. What I want to do is stuff the largest tire I can under the stock-height truck, and still clear the sheet metal and frame/suspension at full lock with the steering. Fitting any size in the rear won't be an issue; it's the front that's the big question here. I have not yet decided on the final wheels, so backspacing is completely flexible. I do not want to trim the exterior front fenders; I don't have inner fenders yet, but am willing to cut/weld/modify replacement inner fenders as-needed to clear. I just want to the tires to stuff and clear as they should. FWIW, the donor chassis is equipped with the F60 RPO code indicating the Heavy Duty Front Spring option (the rear is also G51, or Extra Capacity Rear Springs).

I've searched the web far & wide (various forums), and can't seem to find any real-world fitment answers aside from people using the stock 15" Rally wheels, which I won't be doing. I'll likely be using 17" wheels, but am open to slightly larger ones.

Any real-world experience with specific sizing/backspacing details is appreciated.

Thanks,
Craig

 

[Soundmound]

I bought one of these at the recommendation of @Catbox once you learn the conversion math it helps get you dialed in on what will work. Also try the https://www.speedwaymotors.com/ store for other options that might work better for you.

WheelWise™ Tire Fit Check Mockup Sizing Tool Attachment, Simulates 14-22" Rims, 7-12" Widths, 12-Gauge Steel Construction, For Accurate Tire Size Verification and Maximum Fitment https://a.co/d/eeK1kxS

 

[TotalyHucked]

^Exactly what I was going to suggest. I've seen so few people with a stock height truck anyway, let alone one with 16 or 17" wheels. I think I've seen 1 and he ran a 265/75/16 setup (I only remember cuz that's what came stock on a 99-04 Z71). Couldn't tell ya if he cleared or not it's been so long ago. That tool would be your best friend

I use this site constantly to compare tire sizes:

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.

tiresize.com

 

[Soundmound]

^Exactly what I was going to suggest. I've seen so few people with a stock height truck anyway, let alone one with 16 or 17" wheels. I think I've seen 1 and he ran a 265/75/16 setup (I only remember cuz that's what came stock on a 99-04 Z71). Couldn't tell ya if he cleared or not it's been so long ago. That tool would be your best friend

I use this site constantly to compare tire sizes:

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.

tiresize.com

Nice. I've been using this one but like the look of yours better.

Tire Size Calculator - Compare Tire Sizes | Tacoma World

Tire size calculator compares diameter, width, circumference and speedometer differences for any two tire sizes. Supports tire sizes in metric and inches.

www.tacomaworld.com

 

[legopnuematic]

Love those H2 wheels, I‘ve been keeping my eyes peeled for a set for my 2nd gen ram.

I know you say you aren’t going to run 15”s but, for reference, I have 31/10.5/15”s on a 15x8 with 4.25 back space (wheel vintiques 62 series) on my 76 C10. Stock (non F44) springs with no rubbing or clearance issues at all. I’d think a narrow 32-33“ would be possible if kept inside the wheel arches without too much trouble.

So at a minimum a 31” tire should not be an issue at all.

You must be registered for see images attach

 

[AZ Highlander]

Love seeing your low COG builds from over the years.
I know here in the southwest, most 4x4s have lift to prevent tire rub, but yes, most of the time it is overkill.
What is the greatest benefit of your low COG builds? Off camber dirt roads without roll definitely come to mind, but I am sure there are lots of benefits.
Its great to see builds that aren't the same type of 4x4 we see so often

 

[YourmyboyBlue]

Does anyone know if a 04 canyon standard tire will fit a 85 Sierra classic. Just need to get the truck on a trailer. I don't have access to a flat bed.

 

[Soundmound]

A quick background before asking my question...

I came from 20 years in the Jeep world, and have always loved low-COG builds with minimal-to-no-lift and big tires. It drives me a little nuts to see vehicles lifted higher than they need to be for a given tire size (I see it daily here in East Tennessee, and online everywhere).


A couple of my previous low-COG builds.

Rare military '86 Jeep CJ-10a converted to 4WD, and running 34 x 9.50 "pizza cutter" Swampers on stock-height front springs and no body lift. Wheels are narrow (5.5"?) Toyota steelies from an '80s-era 4-Runner, IIRC.

You must be registered for see images attach

'05 LJ on 1-ton axles, H2 whees with 37" x 12.5" tires and a minimal 3.5" lift. Axle width, wheel/tire sizing, and the AEV highline body kit all helped clear this wheel/tire combination; the flex & tire stuff was amazing. When I was working on this project, people were typically lifting these Jeeps 4.5" to clear much smaller 33" tires, just for some comparative perspective.

You must be registered for see images attach

And back to current day, here's my other daily-driver CUCV, an '86 M1008 on sagged OEM front springs, H2 wheels with ~5 5/8" backspacing. They clear the 55/80R-17 (33" x 10") tires beautifully.

You must be registered for see images attach

So...now my question.

I'm slowly working on this mutt '85 CUCV/C10 project. Here it is sitting on its "new" '86 GMC C15/C10 chassis and "roller" GMT wheels & tires (these will be replaced).

You must be registered for see images attach

Unlike a good portion of the 2WD crowd here, I do not want to lower the truck, unless it's just a little in the back to level things out with the front. What I want to do is stuff the largest tire I can under the stock-height truck, and still clear the sheet metal and frame/suspension at full lock with the steering. Fitting any size in the rear won't be an issue; it's the front that's the big question here. I have not yet decided on the final wheels, so backspacing is completely flexible. I do not want to trim the exterior front fenders; I don't have inner fenders yet, but am willing to cut/weld/modify replacement inner fenders as-needed to clear. I just want to the tires to stuff and clear as they should. FWIW, the donor chassis is equipped with the IF60 Heavy Duty Front Spring option.

I've searched the web far & wide (various forums), and can't seem to find any real-world fitment answers aside from people using the stock 15" Rally wheels, which I won't be doing. I'll likely be using 17" wheels, but am open to slightly larger ones.

Any real-world experience with specific sizing/backspacing details is appreciated.

Thanks,
Craig

Holy hell! I just realized you live in the same town as Brian Harrison of Harrison's Rod & Custom fame. That's on my list of potential move to/dream job relocation spots, lol.

 

[1x1_Speed_Craig]

I bought one of these at the recommendation of @Catbox once you learn the conversion math it helps get you dialed in on what will work. Also try the https://www.speedwaymotors.com/ store for other options that might work better for you.

WheelWise™ Tire Fit Check Mockup Sizing Tool Attachment, Simulates 14-22" Rims, 7-12" Widths, 12-Gauge Steel Construction, For Accurate Tire Size Verification and Maximum Fitment https://a.co/d/eeK1kxS

Thanks! Yes, those tools are pretty slick, and given my less-than-typical question, I thought it might eventually boil down to me getting one of those. I'm certain it would be money well spent vs. guessing at the right combination of wheels & tires, which could be a very spendy mistake.

Love seeing your low COG builds from over the years.
I know here in the southwest, most 4x4s have lift to prevent tire rub, but yes, most of the time it is overkill.
What is the greatest benefit of your low COG builds? Off camber dirt roads without roll definitely come to mind, but I am sure there are lots of benefits.
Its great to see builds that aren't the same type of 4x4 we see so often

Thank you. Functionally, it makes the most sense to keep the COG low to prevent rollovers, provide better handling, etc. Adding some well-thought-out skid plates to slide over rocks vs. lifting more to totally clear them, and you're in business. I'll also mention that, at age 53, I have absolutely zero interest in climbing/jumping into an excessively-lifted vehicle. Secondary to any functional benefits, I really dig the look of low-slung vehicles, and I've felt this way for a couple decades. One of my favorites is Christian Hazel's Jeep CJ-6 that he built for the UOR challenge. IMHO, it's sex on wheels.

You must be registered for see images attach

You must be registered for see images attach

Does anyone know if a 04 canyon standard tire will fit a 85 Sierra classic. Just need to get the truck on a trailer. I don't have access to a flat bed.

Totally off-topic. You'll probably want to start your own thread or do some searching.

 

[1x1_Speed_Craig]

Holy hell! I just realized you live in the same town as Brian Harrison of Harrison's Rod & Custom fame. That's on my list of potential move to/dream job relocation spots, lol.

Yes I am. I've talked with Brian on the phone (super nice/approachable guy), but haven't had the pleasure of meeting him in-person yet. I wasn't able to make the first GM Truck Fair he organized last fall, but plan to make it happen this year.

 

[1x1_Speed_Craig]

Love those H2 wheels, I‘ve been keeping my eyes peeled for a set for my 2nd gen ram.

I know you say you aren’t going to run 15”s but, for reference, I have 31/10.5/15”s on a 15x8 with 4.25 back space (wheel vintiques 62 series) on my 76 C10. Stock (non F44) springs with no rubbing or clearance issues at all. I’d think a narrow 32-33“ would be possible if kept inside the wheel arches without too much trouble.

So at a minimum a 31” tire should not be an issue at all.

You must be registered for see images attach

Thanks for the input. I'm hoping to stuff at least a skinny 33" tire under there. We'll see.

And yes, I love the H2 wheels, too. I obviously had them on my old Jeep (had to have a friend machine out the centers to clear those hubs), and am happy to have them on my CUCV, as well. I have a couple extra very nice H2 wheels in the garage as spares, as they're getting tougher to find in good condition. They're also not inexpensive anymore (nothing is in 2024, but that's a different rant for a different day ).

EDIT: Thanks for the backspacing specifics. Much appreciated!

Thanks,
Craig

 

[TotalyHucked]

Holy hell! I just realized you live in the same town as Brian Harrison of Harrison's Rod & Custom fame. That's on my list of potential move to/dream job relocation spots, lol.

He's a good friend of mine. One of the most genuine guys you'll ever meet and really knows how to put a hotrod together. Greenville is a beautiful area too

 

[Soundmound]

He's a good friend of mine. One of the most genuine guys you'll ever meet and really knows how to put a hotrod together

I've been trying to find a way to reach out in a non creepy way- lol, but his web presence is lacking. Eddy said he would forward my CV if I am serious about it.

 

[Bennyt]

CJ10...those are rare! I've been looking for an export version for a few years with the truck bed. Did yours start off as a tug? I don't think most know how big these Jeeps are.

 

[1x1_Speed_Craig]

CJ10...those are rare! I've been looking for an export version for a few years with the truck bed. Did yours start off as a tug? I don't think most know how big these Jeeps are.

Yes, it was a tug version (CJ-10a). I had two of them at one point. The cab is actually fairly small...standard CJ width/dimensions. The tugs, though, were actually mounted on a shortened FSJ (Full-Size Jeep) frame, but with about 50% thicker frame rails. They're cool little vehicles, and very rare. IIRC, they only made under 3,000 of them originally, and they're incredibly scarce now. Wish I had kept at least one of mine, but that's all hindsight.

The export trucks are very cool. I haven't seen any of this listed for sale in well over a decade, and even then, it was incredibly rare to find one. It may be easier to find one in Australia. I'm not sure what the production numbers were for them.