Author Topic: 3.42 10 bolt max tire size  (Read 1966 times)

Offline johndeeregreg4

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3.42 10 bolt max tire size
« on: September 16, 2019, 02:33:36 PM »
I’m lookin to put on a 6” lift in my K10 with 3.42 gears which would mean 35’s however, I have been told that’s gonna rob my truck of power even with a 350 and TH400 tranny. My other option is a 4” lift with 33’s. What’s the max tire size I can run with my setup?


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Offline JohnnyPopper

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Re: 3.42 10 bolt max tire size
« Reply #1 on: September 16, 2019, 03:25:48 PM »
What year is your K10?

Are the stock size 31" or what are you running currently?
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 johndeeregreg4

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Re: 3.42 10 bolt max tire size
« Reply #2 on: September 16, 2019, 03:30:36 PM »
It’s an 85 and yes I’m running 31x10.5x15


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Offline Irish_Alley

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Re: 3.42 10 bolt max tire size
« Reply #3 on: September 17, 2019, 07:07:17 AM »
any increase in tire size will rob you from the take off power you used to have. that being said your rpms at cruising will be lower. ive seen people run 38s on that low gear ratio and while its ok for road use i wouldnt run it in the mud pit but then even if you find you need the rpms you can always shift into 4 low. just wouldnt do it on the road
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline johndeeregreg4

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Re: 3.42 10 bolt max tire size
« Reply #4 on: September 17, 2019, 07:44:04 AM »
Ok good to know! The thing I’m also concerned about is the strain that the tires will cause on the drivetrain. Is it enough to destroy the diff or tranny/ both?


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Offline Irish_Alley

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Re: 3.42 10 bolt max tire size
« Reply #5 on: September 17, 2019, 11:02:29 AM »
if youre not abusing it then no. the th400 will be able to handle the 35s. the OD in the 700r4 is known to burn up due to the larger tires but you wont have that issue. as far as the axle youll be ok, but then if you abuse it then something might give sooner or later
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline JohnnyPopper

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Re: 3.42 10 bolt max tire size
« Reply #6 on: September 17, 2019, 12:55:11 PM »
The weak link is the driveshaft and U-joints, regular and CV. (constant velocity- which I am derelict to find a lube fitting tip to get into those tight zerk fittings!)

If you have the type that can be lubed up, stay on it along with the spline joints, front and back.
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 Irish_Alley

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Re: 3.42 10 bolt max tire size
« Reply #7 on: September 17, 2019, 01:48:51 PM »
yeah forgot about the front driveshaft. as you lift it up to the 6" youll be maxing out the front driveshaft, it will still work ok but after some time in 4wd the splines will start wearing down because the spline contact is very min. but again i think its going to depend on how hard you drive it in 4wd. though it seams most people who run 38s and 6" lift without a new front shaft will tend to see this issue more than those running 35s
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes