Taller tires for my 1976 K20

[Griffbl]

Gents- My stock 1976 K20 has Hubcaps and 7.50x16 Tires. They look like tires for a tractor, and ride accordingly. Looks like i can get some better riding all terrain tires in 235x85/R16's that are essentially the same height. I believe these rims are stock and original. Can I squeeze 255x85/R16's on these rims? Many thanks.

 

[Ricko1966]

Can you? Sure should you I don't think so,but I've probably done worse.

 

[Griffbl]

Or are there Steel 16" rims which Wheel Vintiques or someone makes that might be a bit wider, (so I could use taller tires that are of course slightly wider) that would also accept my factory hubcaps?

 

[Ricko1966]

Or are there Steel 16" rims which Wheel Vintiques or someone makes that might be a bit wider, (so I could use taller tires that are of course slightly wider) that would also accept my factory hubcaps?

Sir I stand,well actually lie on the couch corrected. I was doing my own mental math,but I looked up what rims you truck should have had and they aren't 5s they're 6s I think you'll be fine.

 

[bucket]

Man, I love those old Power Kings. I wish they still made them so I could buy more of them.

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Even if you have the 6" or the 6.5" wide rims, the 235's or 255's will fit and work just fine though.

 

[AuroraGirl]

Gents- My stock 1976 K20 has Hubcaps and 7.50x16 Tires. They look like tires for a tractor, and ride accordingly. Looks like i can get some better riding all terrain tires in 235x85/R16's that are essentially the same height. I believe these rims are stock and original. Can I squeeze 255x85/R16's on these rims? Many thanks.

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The only way your truck came with 16 inch rims would mean it came with tubed bias ply tires. You should not use a radial tubeless tire on them , its not safe. The use of a larger, especially, radial tire could crack or lead to failure over time. But if they werre aftermarket, its an entirely different story. a late 80s square with 16 inch wheels would fit your caps and also be supportive of radial tires. fords until the late 90s also work. Dodges for the same period also work.

 

[Grit dog]

@Griffbl
First, beautiful truck!
Second, don’t let some of the posts here complicate or confuse you or what you’re asking about. Theyre simple questions.
Yes 255/85s will be fine on those rims.
Yes you can get about any size steel rim you want. In 15”-22” dia up to 12” wide or wider.
(20x9 in my picture)

 

[AuroraGirl]

dont let some bad faith hack convince you to ignore potential safety issues, it only takes a small amount of checking on what you have to know what your next move is.

 

[bucket]

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The only way your truck came with 16 inch rims would mean it came with tubed bias ply tires. You should not use a radial tubeless tire on them , its not safe. The use of a larger, especially, radial tire could crack or lead to failure over time. But if they werre aftermarket, its an entirely different story. a late 80s square with 16 inch wheels would fit your caps and also be supportive of radial tires. fords until the late 90s also work. Dodges for the same period also work.

I'm curious why you say this? This is the first I've heard of not being able to run tube or tubeless (radial or otherwise) tire on a standard type rim.

I *think* the original 16" rims in '75 would have been of the locking ring variety? So the rims in question are probably from a later truck.

 

[AuroraGirl]

I'm curious why you say this? This is the first I've heard of not being able to run tube or tubeless (radial or otherwise) tire on a standard type rim.

I *think* the original 16" rims in '75 would have been of the locking ring variety? So the rims in question are probably from a later truck.

good point, you are right i think on the rim thing. He should be fine then because I believe 1981 or 1982 you could start equipping radials iirc On squares?
But its because radials hug a wheel much differently than bias plys do, and there is an extra bead that seals up against a radial tire that is absent in old enough steel rims, iirc its similar to how 16.5 lack a feature like that. But I could be mistaken there.

If you ever find a comparable 197_ 15 inch wheel and compare to a similar size/appplication 1980s 15 inch wheel, idk what off but just example, is that the 80s wheel will be heavier. its stronger.

https://sites.sema.org/ext-assets/councils/pdf/WTC-2011-05-Bias-vs-Radial-Tire-Wheel-Fitment.pdf

I only bring it up here because he has a really nice shape 70s 3/4 ton and he was looking to put taller and wider tires on the wheels. If they were old enough to be only for a bias ply, he could suffer failure with a payload or when driving but if he had half ton or maybe even kept to The same size and only drove it unloaded idk. But yeah

 

[Griffbl]

thank you so much for the GREAT information! Very useful and helpful. I will try to find some 16" Steel wheels which will fit my truck, accept larger tires, and my factory hubcaps. Thanks again!

 

[MidneightReider]

don’t let some of the posts here complicate or confuse you or what you’re asking about. Theyre simple questions.

This is a method of isolation from other people's input that narcissistic people use because they want to feel superior.

Forums are for discussion, not suppression of information based on one person's opinion. Accept all input, especially cautionary, then dissect the totality of all that input and come to your own conclusions. What some would consider unsafe, others wouldn't bat an eye at, and that's ok.

 

[AuroraGirl]

This is a method of isolation from other people's input that narcissistic people use because they want to feel superior.

Forums are for discussion, not suppression of information based on one person's opinion. Accept all input, especially cautionary, then dissect the totality of all that input and come to your own conclusions. What some would consider unsafe, others wouldn't bat an eye at, and that's ok.

what a measured response, thank you. Dont worry about what bucket says about you behind your back, youre all right! (Jk bucket never did that lol!)

 

[AuroraGirl]

thank you so much for the GREAT information! Very useful and helpful. I will try to find some 16" Steel wheels which will fit my truck, accept larger tires, and my factory hubcaps. Thanks again!

Bucket raised a good point, there could very well be later square rims already. If you have a spare tire that matches, maybe dismount the tire on it and check around the barrel for a stamped number, here is a 1983 suburban k10 6 lug wheel

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In addition to the size being listed as 15x8, there is an "83" upside down relative to that stamp near it. thats the year. If gm followed this convention for all the trucks in the generation, your wheels likely contain a code like that. I wouldnt hestitate using mid 80s and newer steel 8 lug rims with radials since they would have been able to come with them brand new.

 

[MidneightReider]

I'm curious why you say this? This is the first I've heard of not being able to run tube or tubeless (radial or otherwise) tire on a standard type rim.

I *think* the original 16" rims in '75 would have been of the locking ring variety? So the rims in question are probably from a later truck.

I don't know a ton about vintage truck wheels but I am a certified motorcycle technician and I can tell you that the reason many don't run tubeless tires on wheels that weren't designated is because they don't have a bead retainer formed or cast in the wheel. Obviously things become far more critical on a motorcycle but the danger lies where a tire finds itself at low pressure and experiences a side load for example during cornering, and suddenly de-beads itself and instantly loses pressure. I do know that modern car and truck wheels have a bead retainer which is why we hear a 'pop' when the bead seats. If older wheels don't have that bead retainer, and some probably don't, a tire without a tube holding the bead against the lip would certainly run that same risk at low pressure of suddenly losing all pressure during cornering, and that could be unsafe.

And in expanding on my previous post, yes I have run tubeless motorcycle tires on vintage cast aluminum wheels that don't have a bead retainer because I'm not particularly intelligent or easily spooked, but I know plenty of riders that would never, ever do it. Everyone's comfort level is different.