78 c20 10 inch wide wheels

[squarebuddy88]

So, I need some new tires for my 78 c20 that currently has stock suspension. Im looking into getting new wheels at the same time. I want a wide wheel and tire look in either a 16 or 17 inch wheel. Ive been thinking I want to go for the 10 inch wide wheel but im concerned about the fitment on the front of the truck. Ive seen some other 2wd squares on the web with 10 inch wide wheels front and rear and supposedly theyve had no problems. I want matching wheels and tires on all four corners. From my research, the tire sizes that are more affordable and easily available are 275/70/16, 285/65/17, and 285/60/17. IF I was to choose any of these tire sizes and pair them with a 10 inch wide wheel, what offset and backspacing would I need to ensure they dont rub? I could also possibly go with a 9 inch wide wheel if I go 17's because those seem more common than the 17x10. Im just hoping the overall look would be very similar. My first choice in wheel is the procomp 69 series vintage polished wheels, or possibly a steel wheel in white. I like the idea of a wheel in something other than steel because in theory it should be easier to take care of and prevent corrosion in the long run. If anyone has pictures of an 8 lug truck with a similar setup please post pics and tell me how it went. Thank you in advance!

 

[bucket]

For a little while I had 33"x12.5's on the rear. The wheels were 16.5x9.75". I'd have run them on the front too, if I'd had a couple more decent tires.

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After that, I ran a full set of 16.5x9.75" wheels with really old 12.00x16.5 tires. They were very close in size to the modern 33"x12.5" tire. They barely cleared the front fenders, but they did clear.

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Your truck looks like it might be slightly lower than mine in the front.

 

[Big Chip]

If all else fails you could buy something like this or find a tire store that has one:

Wheel Tire Combination Measuring Fitment Tool compatible for 5x4.5 5x5 5x4.75 4 separate

Wheel Tire Combination Measuring Tool Gauge Fitment Tool Gauge Set For 5x4.5 hub. Welcome to choose Wheel Tire Combination Measuring and other performance auto parts, tuning car parts, engine accessories online on maxpeedingrods with best price. one year warranty.

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[Alaska 79 K-10]

I think you will find that the most you can safely go on backspacing is 4 1/2” To 4 3/4”. Otherwise you will run into the tie rods. The larger wheel diameter you stated may give you an added advantage. Compare your current wheel to the tie rod, then measure your backspacing.

 

[squarebuddy88]

yea my truck does seem to sit pretty low in the front, im not sure what thats all about.

Alaska 79 K-10​

when you say the most i can go is 4.5-4.75, do you mean i shouldnt go more towards 5 inches or more towards 3 inches, just so im clear?
So if i was to find a wheel in a 17x9 OR 17x10 with 4.5 to 4.75 backspacing i should be ok?
It looks like bucket fit a 12.50 wide tire on a 9.75 wide wheel so theoretically with a smaller width and diameter tire i should be ok?

 

[Craig 85]

Here's my '85 K30 with 16x10's 4.5" of BS and 305/70R16 tires (photo #1).

Those measure out closely to the 33x12.50x16.5's I had on my '80 C20 3+3. The 16.5x9.75" wheels back in the day had 4.75" of BS. A 33" tire with a 16x10 will definitely rub in the front. On my '80, I added Air Lift air bags to my front coils and got about 2" of lift. I added a 2" block to the rear. I had to do a minor trim to the front fender lip.

Photo #4, I had the old 33's on my Brown/Tan '85 C20 before they went on the 3+3. No lift on that one, but had to trim the fender.

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[squarebuddy88]

So how about a 275/70-16 on my stock appearing 16 inch wheels? Theyre probably somewhere between 6-7 inches wide if i had to guess. I know a lot of guys run skinny 16 inch wheels from some of the more modern chevys with 285-75-16s on them, granted they usually have a lift, but my point is the 275 tire should fit ok on my wheels. Another idea i had is some dodge 17x7.5 steelies with some chevy center caps with a set of 285-65-17, but i cant seem to find those wheels locally.

 

[bucket]

So how about a 275/70-16 on my stock appearing 16 inch wheels? Theyre probably somewhere between 6-7 inches wide if i had to guess. I know a lot of guys run skinny 16 inch wheels from some of the more modern chevys with 285-75-16s on them, granted they usually have a lift, but my point is the 275 tire should fit ok on my wheels. Another idea i had is some dodge 17x7.5 steelies with some chevy center caps with a set of 285-65-17, but i cant seem to find those wheels locally.

275/70 should work fine. 285/75 does indeed fit on stock width rims and you should be able to fit that (more common I believe) size if that's what you prefer.

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[Craig 85]

I had an '88 C20 Suburban years ago. The original owner had lowered it and was running 275/70's on a 16x8" wheel. Back then those tires only came in load range "C". The only one on Tire Rack that is load range "E" is the BFG All Terrain.

 

[squarebuddy88]

That brings up another question, Craig 85. A lot of the tires im seeing dont list the load range or ply rating, but instead just list the load index. Correct me if im wrong, but would the tires be "acceptable" for the truck so long as the load index combined for four tires is equal to or higher than the gvwr of the truck? From what i gather, it seems like the load range kinda tells you how stiff the tire will be, and the load index tells you how much weight it can safely hold. Ive seen a lot of the tires im looking at, their load index says they can hold roughly 2600lbs per tire. multiply that by four and thats 10,400lbs combined. I theory, that should be good enough when compared to the weight rating of my truck at 8200lbs. Does this all sound right?

heres a link to one of the tires i was looking at for reference https://www.carid.com/gt-radial-tires/savero-ht2-1912634523.html?child_id=2229321643

 

[bucket]

Driving characteristics is something to consider besides overall weight rating. When towing or hauling, a lighter rated tire that's running anywhere near capacity isn't going to handle as well as a tire with more capacity. That lighter carcass can give you a very unstable feeling, despite being under the weight rating.

 

[Craig 85]

That brings up another question, Craig 85. A lot of the tires im seeing dont list the load range or ply rating, but instead just list the load index. Correct me if im wrong, but would the tires be "acceptable" for the truck so long as the load index combined for four tires is equal to or higher than the gvwr of the truck? From what i gather, it seems like the load range kinda tells you how stiff the tire will be, and the load index tells you how much weight it can safely hold. Ive seen a lot of the tires im looking at, their load index says they can hold roughly 2600lbs per tire. multiply that by four and thats 10,400lbs combined. I theory, that should be good enough when compared to the weight rating of my truck at 8200lbs. Does this all sound right?

heres a link to one of the tires i was looking at for reference https://www.carid.com/gt-radial-tires/savero-ht2-1912634523.html?child_id=2229321643

I agree with Bucket. The extra plies an LT tire has will increase your sidewall stability. I understand your math with the weight rating your linked to. The issue would be does the tire have the weight capacity for the rear axle? If your truck still has the tag on the driver's door, it will tell you. See mine below. The GAWR RR (rear axle capacity) is 6084 LBS., front is 4500. In my case I could install the tires on the front, but they would not meet the rear axle capacity. The Wildpeak AT3's I have on my truck have an index of 124 (3527 LBS per tire for a SRW).

I listed the index chart for you. I looked on Tire Rack and all but the BFG are an index of 114. BFG is 119. If I remember correctly, this size tire was originally used on the 90's Toyota Land Cruiser/Lexus SUVs.

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[squarebuddy88]

GAWR for the rear shows 5560, GVWR is 8200. my only issue here now is trying to save money. technically the 116 load idex tires almost meet the rating needed for rear GAWR of 5560. Ill probably just go with the load es at 120 index or so that way i dont have to worry about. I think my wheels say theyre rated for 2800 something pounds, so i dont really need the E's if i keep these wheels but it wouldnt hurt to have stronger tires. I wonder if the E rated tire should last longer being its rated for more weight than this truck will ever see?

 

[Grit dog]

GAWR for the rear shows 5560, GVWR is 8200. my only issue here now is trying to save money. technically the 116 load idex tires almost meet the rating needed for rear GAWR of 5560. Ill probably just go with the load es at 120 index or so that way i dont have to worry about. I think my wheels say theyre rated for 2800 something pounds, so i dont really need the E's if i keep these wheels but it wouldnt hurt to have stronger tires. I wonder if the E rated tire should last longer being its rated for more weight than this truck will ever see?

Nothing wrong with 116 load tires you're running provided you're not hauling alot of weight in the bed at high speeds or long distances.
And you're spot on, that apples to apples higher load index tires last longer than lower load index.
And I'm not advocating what I'm about to say, but I spent alot of years and alot of 1/2 ton trucks (company trucks, heavy construction work) getting tires overloaded regularly with little ill effects. I've been known to put 60 psi in 44 psi rear tires and tow very heavy loads (for a 1/2 ton) for long distances at highway speeds and mountain passes. Again, not recommending, just relating.