Biggest tire size on stock 18' Rim?

Sniperdan · April 1, 2020

What is the biggest tire size I can put on my 18" stock rims without having to do a lift kit or turn up the torsion bars?

What about with just a torsion bar adjustment?

2020 3500 AT4 Crew Cab Long box

mkeddie · April 1, 2020

Also interested in same

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MesaRat · April 3, 2020

according to my service advisor you should be fine up to a 295/65/18.

the optional stock 20"s (275/65/20) are a ~34.1"D and ~10.8" W tire and the 295/65/18 are ~33.1"D and ~11.6"W

i am thinking of trying a 285/75/18 which is ~34.8" D and 11.2"W b/c I want more sidewall or possibly a 295/70/18. but i don't know if this will work for sure, just suspect it will based on closeness of diameters to the OEM 20".

before i decide on a final size i will cut a wood block/shim to the size of the added radius and another for the added width on the inside and turn lock to lock stopping at numerous points to check if there is any area(s) too close or in contact with the inner fender or suspension

Sniperdan · April 3, 2020

8 hours ago, MesaRat said:

according to my service advisor you should be fine up to a 295/65/18.

the optional stock 20"s (275/65/20) are a ~34.1"D and ~10.8" W tire and the 295/65/18 are ~33.1"D and ~11.6"W

i am thinking of trying a 285/75/18 which is ~34.8" D and 11.2"W b/c I want more sidewall or possibly a 295/70/18. but i don't know if this will work for sure, just suspect it will based on closeness of diameters to the OEM 20".

before i decide on a final size i will cut a wood block/shim to the size of the added radius and another for the added width on the inside and turn lock to lock stopping at numerous points to check if there is any area(s) too close or in contact with the inner fender or suspension

One local tire shop assured me that the 285/75/18 would work no problem without having to turn up the torsion bar or add a lift. Said he has put them on several trucks. My dealer says they won't fit. Another tire shop wasn't sure. In the end I decided to stay with the stock size 275/70/18 and maybe upgrade size next time I need tires.

Big Whiskey · April 4, 2020

The 2015-2019 HD's can run a 258/75/18 or 295/70/18 on stock wheels at stock height. The 2020's seem to have more room than the previous generation, so I don't see any reason why those sizes wouldn't work. Could probably even run a true 35x12.50x18 on stock wheels with a few torsion bar cranks.

Dunn · April 7, 2020

stock 18s seem kinda small in wheel well...sure seems like there is a lot of spare room in these trucks with 18s....I would think 1 or 2 sizes up no problem.....here ya go....should have no issues whatsoever

Edited April 7, 2020 by Dunn

mkeddie · April 8, 2020

stock 18s seem kinda small in wheel well...sure seems like there is a lot of spare room in these trucks with 18s....I would think 1 or 2 sizes up no problem.....here ya go....should have no issues whatsoever

That thread is all over the place as far as rim size and lift and I don't think a single post was stock 18 and no lift

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Dunn · April 8, 2020

sure there is....since there is a lot of guys running 20s and aftermarket just have to sift thru them....there is a guy there with 295/70R18 on stock rims/stock susp and no rubbing and has pics...just trying to help man this doesn't even pertain to me.....I just ran across it

Edited April 8, 2020 by Dunn

Sniperdan · April 8, 2020

2 hours ago, Dunn said:

sure there is....since there is a lot of guys running 20s and aftermarket just have to sift thru them....there is a guy there with 295/70R18 on stock rims/stock susp and no rubbing and has pics...just trying to help man this doesn't even pertain to me.....I just ran across it

That was the info I was looking for. Too late though, I already replaced them with stock size. Maybe I will upgrade them on the next set of tires. Thanks for posting this.

mkeddie · April 9, 2020

Thanks Dunn....I have seen nearly ever post in there and never saw that post guess I'll have to skim thru it and find him

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Dunn · April 9, 2020

14 minutes ago, mkeddie said:

Thanks Dunn....I have seen nearly ever post in there and never saw that post guess I'll have to skim thru it and find him

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its slim pickings for sure but like every thread they veer off.....the OP was asking same question you guys are and he got all that!

page 3 his name is roadrunner45

mkeddie · May 21, 2020

So I fit 305 70 18s just barely fit but they do

https://r.tapatalk.com/shareLink/topic?url=https://www.gm-trucks.com/forums/topic/238565-my-upfitting/&share_tid=238565&share_fid=33003&share_type=t&link_source=app

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kf9yr · May 21, 2020

So I fit 305 70 18s just barely fit but they do
https://r.tapatalk.com/shareLink/topic?url=https://www.gm-trucks.com/forums/topic/238565-my-upfitting/&share_tid=238565&share_fid=33003&share_type=t&link_source=app

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Any rubbing at full lock?

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