Author Topic: tire size questions  (Read 2441 times)

Offline JohnnyPopper

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tire size questions
« on: January 04, 2024, 08:59:16 PM »
While on the subject, my 33" KOA's have a few miles to go before replacing.

Oh, btw, '78 K10 bone stock.

I believe I have 15 x 11" wheels, and thought I might try 35" on the next go round.

Any thoughts on if the 35" being wider and the wheel being the same might bow out the sidewalls?

I did a clearance test and I don't think anything will rub.

Thanks in advance for any guidance!!!
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Captkaos

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Re: tire size questions
« Reply #1 on: January 05, 2024, 07:52:18 AM »
35" wont fit on a bone stock K10 without tearing into the rear fender.  I would imagine these have some offset on them and if that is the case 35's will most likely hit the bottom of the front fenders
what is the width of the 33's on there now? You can technically get the same width on the 35's, but that extra 1" of circumference is the issue.

Offline JohnnyPopper

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Re: tire size questions
« Reply #2 on: January 05, 2024, 08:08:45 PM »
With her current stance I can't see how that would happen. But I just don't know.

Oh, so not the top of the fender, but the skirt nearest the wheels?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Captkaos

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Re: tire size questions
« Reply #3 on: January 06, 2024, 02:55:23 PM »
Yes, It typically hits at the rear of the fender opening.

Offline Mike81K10

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Re: tire size questions
« Reply #4 on: January 06, 2024, 03:34:48 PM »
I RAN 33.50"s on my K10 in the past and they fit well.
"Tell me and I forget. Teach me and I remember. Involve me and I learn." -Benjamin Franklin

Offline JohnnyPopper

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Re: tire size questions
« Reply #5 on: January 09, 2024, 06:32:56 PM »
Yes, It typically hits at the rear of the fender opening.

So I guess it happens while suspension is compressed, correct?

What if you're only on street?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline Captkaos

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Re: tire size questions
« Reply #6 on: January 10, 2024, 08:49:36 AM »
yes but it wont take much compression, driving out of a sloped driveway could do it.
If it ever bites that part it will pretty much ruin a fender,  If you feel like it is a risk you can take, that would be up to you.

Offline VileZambonie

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Re: tire size questions
« Reply #7 on: January 16, 2024, 03:26:11 PM »
Unless you plan on lifting it two more inches, stick with the 33"S
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline ehjorten

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Re: tire size questions
« Reply #8 on: March 01, 2024, 11:16:17 AM »
33" tires on my '77 K20 with stock suspension. No way 35" would fit without a lift.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline JohnnyPopper

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Re: tire size questions
« Reply #9 on: June 12, 2024, 10:36:55 PM »
Hey so looking at my girls sneakers, the 33" aren't long for this trip.

Would really like to go with 35" tires so started looking into options for raising her up a tidge.

My buddy at A&B Truck recycle's recommended Skyjackers.

Looked at their 'softride' approach to how they make their leaf springs-sounds impressive!

They have a 2.5" lift kit. Springs for the front, blocks for the rears.

It includes shocks front and rear, but I may decline, don't do any off road.

Do any members have an opinion on this brand or something else?

TIA as always, and with respect!
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline JohnnyPopper

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Re: tire size questions
« Reply #10 on: June 26, 2024, 07:05:54 AM »
I guess no one here has used Skyjackers....? Is it b/c of their profession of Jesus?  ;)

Well, the leaf springs came, and it looks like the fronts are seriously arched. The stock setup is from GM on a K10, which in fact, have a negative arch on the front. I realize that they are not under load, but they look too high.

My goal is to add 2.5 inches to accommodate 35" tires.



1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline berserk

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Re: tire size questions
« Reply #11 on: June 27, 2024, 12:46:07 AM »
I installed new Skyjacker 2.5 leaf springs on my K10 and still couldn't clear 33s my tires were hitting both sides of the front fender. I still had to trim the fender in the end just to clear 33-in tires so I have no idea how others are doing it with a stock spring setup.

I will say the soft rides improved my right quality significantly over the stocks, but they have a soft spring rate and when I added my winch bumper and 12K winch The front end rode a lot harsher. Same happened when I loaded down the bed, I may have put 500 lb in and it was almost sitting on overloads. They are made to ride good but definitely not to handle heavy loads.
76 Chevy k10 350/th350/203 part time. Vortec head 350 Dana 60 w/Detroit, 14 bolt Tru Trac, 33" Micky T. Mudders.

Offline JohnnyPopper

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Re: tire size questions
« Reply #12 on: June 27, 2024, 09:03:44 PM »
Thanks for the reply and back story!

I've had 33" on this truck with no problems at all. Seems odd that you would have clearance problems.

Did a PO perhaps lower the truck?

My tires have so much clearance I thought about trying 35" with stock springs until the 'brain trust' kicked in.

With your description of a soft ride I feel more confident that I'm on the right track.

I don't off road so I am just looking to have a more comfortable ride.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline berserk

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Re: tire size questions
« Reply #13 on: June 28, 2024, 01:49:23 AM »
The K10 had wore out stock suspension 2 years ago. In the last 2 years I replaced all the suspension bushings, new 2.5 soft rides, 1 ton swap etc. I didn't even test fit the 33s until everything was done. Going by this site which has vast knowledge I assumed I would fit the 33s with a ton of clearance especially with the 2.5" lift. The truck was on flat ground on its own weight and the tires hit the front and then the rear of the front fenders when attempting to turn lock to lock. I had to trim several inches off both sides and was able to clear by a few inches but I suspect if I get the truck twisted up in a gully or ditch it may still touch.  At this point there is nothing in the running gear I have not replaced with new. And the clearance is now even less after adding my winch and winch bumper but it never touches running around town. I haven't even had a chance to take it off road yet
76 Chevy k10 350/th350/203 part time. Vortec head 350 Dana 60 w/Detroit, 14 bolt Tru Trac, 33" Micky T. Mudders.

Offline VileZambonie

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Re: tire size questions
« Reply #14 on: June 29, 2024, 06:14:13 AM »
Regardless of the soft ride springs, it will not make the ride better. Once you start going up higher, the ride gets bouncier. Billsteins will help
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10