OE tire size?

[Rusty Nail]

'77 C20 that I am near convinced was equipped with the "trailering special" package. VIN plate only bothers to tell me 8.75x16.50 which was the OE wheel size? Does anyone know the tire size that was Original Equipment?
Please and thank you.

 

[bucket]

Sure that's not the tire size? It sounds about right.

Most stock rims were only around 6.5 inches wide. There were 8.25 and 9.75 available, but those were fairly rare.

 

[Rusty Nail]

LoL? No? (I'm not sure) Lmao. Seems that it's missing a few digits or something to be a tire size...I only assumed it was wheel size but I thought they were mostly 16.5 x 6 ? Ok, 6.5...whatever. Some ****, like i'm hip or something...How can it not list an aspect ratio? Are you trying to tell me the OE TIRE SIZE is 8.75 x16.50? Wtf does that mean Bucket? Wtf do those numbers represent? LoL that's retarded!
I have found 225/75/15 for later c10s...

What is the metric equivalent? I understand that.

That is telling me the diameter of the frickin hole in the middle and the width? More information is necessary. I consider that as inconclusive. If not width than what? Sidewall height? Bull. More information is necessary!

"8.75x16.50 pressure 40
8.75x16.50 pressure 60"

I searched that on the inter webs and it returned a search of THIS THREAD (skeery)
Wtf. Are you tellin me I am the only guy in the entire world, ever!, to ask that question?
Oh wait...I guess the standard/metric thread conversion coincided with tire size measurements as well. FML.

 

[GTME94]

You can go to the GM Heritage website and see if the information packet for your year truck lists original tire sizes.

 

[HotRodPC]

Yikes !!! You seem thoroughly disgusted about not being able to find the info. Good suggestion about the GM Heritage sight. Should be able to find OE tire sizes there. How about your label in the glove box? That usually has the OE tire size listed there too. Your year model may have the SPID label on the left inner fender too. I've got to run out on a tow and have some fires to put out today. If you don't have the info later tonight, I'll do some digging. Just for clarification, you are still running the stock OEM 16.5 rims? I do know for 77 the C20's did get the 16.5 wheels.

 

[Rusty Nail]

I've been to the heritage center and can't yet convince my android to open the .PDF. Thanks for the suggestion.
My RPO sticker is M.I.A. and that hootis under the hood only tells me how to work a jack.
I became curious to know in order to figure speedometer error. Outside of that IDGAF. I maintain that it has no choice but to do my bidding. I'm the guy with the big tool box full of shiny instruments.
I have ancient Progressive 16x8s, they're pretty cool.

 

[bucket]

There were numerous tire sizes in the old days that did not list an aspect ratio, and a lot of them are still found today. The most common would be the old VW size, 155R15. A million different bias ply sizes from the 60's and earlier, like 7.25X14, 5.75X14, etc. Truck sizes were a little different, but similar even with the later 16's. For example, my dually runs 9.00x16's. There were also .50 sizes (7.50, 8.50, etc.) that were a smaller diameter than the .00 sizes (8.00, 9.00, etc.) and all of them used to be common.

 

[bucket]

And the most common stock size for 16 inch was a 235/85/16. Those are limited in selection these days, but 265/75/16 would be a good modern day equivalent. About the same height, just a little wider.

 

[bucket]

http://www.millertire.com/products/trailer-tires/8-75-16-5/8-75r16-5-firestone-transforce-ht/

 

[Rusty Nail]

Ahh! 235/85. That's a substantial thing. Lemme see...stock was a 31x9?
I bought 255/70 and traded an inch up for an inch wider? Cool deal. I happen to have a BRAND NEW pair of 2 inch adjustable drop shackles layin around. Ima toss those pups on and it'll end end lookin pretty tough, ya reckon? All I have first hand to go by is my '97...shackles did that one a world of good, initially. I figure Babe the Blue Ox will terrorize just fine with a 0-2 drop. Plus the tires? Yessirrr!!!

Thanks Bucket.

Very sneaky edit, I see what you did there!

 

[Rusty Nail]

Haha... I got a return return for a "steer tire for old farm trucks" last night. That did NOT sound cool at all!

 

[Rusty Nail]

http://www.petestirestore.com/875x165-Akuret-Tracker-Plus-XL-10-Ply-TL_p_7459.html

Oh noooooo! I don't think so Mr. Bill!
I need higher revs/mile than OE. Babe's ass is FAT. Not a lot of weight reduction to be had.

Now I am convinced enough to mount these new tires. My 2wd has no business going higher...it has a Corvette engine in it for cryin out loud!

I have been using this tool extensively but either it requires more numbers to work or I'm too stupid to do it.
http://tire-size-conversion.com/tire-size-calculator/

I wanted fatter looking (more sidewall bulge), and enough shorter to increase my final drive ratio a marked amount without getting lowpro ghetto as it MUST maintain function as a truck. No springs+hangers for the '77. A.T. for me! Must have curb/parking block clearane in a hurry. It's not a racecar...yet. Seems like every single thing I touch ends up embarrassing some jagoff at a red light eventually. /shrug

Don't hold your breath for a timeslip anytime soon. :devil:

I knew I should have bought that Torker...
That's your cue Mr.Bill, light em up!

 

[Rusty Nail]

265/75 is a 31x10....a 255/70 makes 5% more revs/mile at 30x10. 10% less sidewall = less deflection/better handling - i'm all about it.

Now to calculate my true gear ratio!
Thanks Bucket.