35x12.5 R18 on 2015 Sierra 2500HD

matt-atwood · August 25, 2018

I’ve got a 2015 Sierra 2500HD and I’m going to be leveling it(2 to 2.5”) and putting some bigger tires on it. Most likely Trail Grapplers, but still considering Open Country MT. My goal is 35x12.5 on the stock 18” wheels. Two concerns I have even after reading what feels like 1000 forums:

1. Is the 12.5” wide tire going to be an issue with the stock 8” wheel? I’ve read mixed reviews with some saying they know people that have no issues with the wheel size, with some even being on 7” wheels. Others act like it’s crazy talk and say that the 12.5” tire on the 8” wheel is way too much and not on the “approved” rim size of the tire. The approved rim size is 8.5”. Is that .5” really that much of a difference?

2. Second concern is rubbing to the point trimming is needed. The ideal goal is no rubbing what so ever. Some people have claimed slight rubbing at full lock and others have claimed no rubbing due to the stock offset being just right. I suppose slight rubbing at full lock would be tolerable though.

My back-up plan is going with 285/75 which would measure about 35x11.2. I just love the looks of those 12.5’s.

I’m hoping there’s someone out there with experience with exactly this issue, or know a buddy with the same set-up and can fill me in.

Waaazooo · August 26, 2018

Depending on the offset of the wheel will determine how bad you rub and where. I rub everywhere and even moved my bumper forward about 3/4” and leveled about 2.5 inches.

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Gear_Jammer · August 26, 2018

I have 17's but was in your situation about a month ago. I knew I wanted to go bigger, but didn't want to deal with the issues that go along with going too big. I ended up going with 285/75 17 Ridge Grapplers, cranking on the keys a little and getting it aligned and have been very happy. I got the increased height I wanted and most of the width without any problems. The pics below were taken before adjusting the keys - it looks closer to level now. All these trucks seem to be setup a little different, so for whatever reason, what rubs on one may be fine on the other. Best of luck.

rocnrol · August 26, 2018

2015 2500, with 305-70/18's on the factory wheels. These are a true 35-12.50 tire.

I'm pretty sure the stock 18's are 9.5" wide wheels

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zmnypit · August 27, 2018

I put 35x12.50 MT's on my factory 20" wheels with 7 turns on the stock keys and shock extenders with no rubbing and no issues.

Damooch · August 28, 2018

I have 285/70/18 duratracs on my 2017 2500hd. It has a CCM level kit. I rub at full turn left even with trimming air Dam. Also going left at full compression tires hit. I have Fox shocks on also. It’s tolerable but gets on my nerves at time. Offset of aftermarket rim is -18.

Seapacer2 · September 20, 2018

Damooch,

You mentioned that you have a CCM level kit, what components are you utilizing on your 2017? I have a 2018 that I want to level, it has about 3-3.25" difference between the front and rear. I have sent a few emails out to different vendor and asked a few questions, I'm not sure if I can make up the difference by just cranking up the adjusting screws on my torsion bars, and I'm only going to be able to obtain about 2" from this, along with loosing ride quality. I have 18" OEM chrome wheels and the ultimate goat is also to get 285/70R18 size tires.

Criscone · September 20, 2018

Damooch,

You mentioned that you have a CCM level kit, what components are you utilizing on your 2017? I have a 2018 that I want to level, it has about 3-3.25" difference between the front and rear. I have sent a few emails out to different vendor and asked a few questions, I'm not sure if I can make up the difference by just cranking up the adjusting screws on my torsion bars, and I'm only going to be able to obtain about 2" from this, along with loosing ride quality. I have 18" OEM chrome wheels and the ultimate goat is also to get 285/70R18 size tires.

I also just want 2” up front, so the rear is 1” taller than front. From what I’ve read is stock keys will get you almost 2”, and just add shock spacers at most. Anything beyond that it’ll ride awful, and all angles are extremely bad. I turned stock keys 7 turns and got 1.5” so far. Have a little more to go, hoping to get the full 2” I’m looking for. So far ride hasn’t changed much

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Seapacer2 · September 20, 2018

Criscone,

That is a good start, once you get the additional .5" please post to let us know what effects it has on your ride. I agree with you, anything over 2", you will start to loose ride quality, you CV angles start to increase beyond acceptable values. One vendor I talked to said that on these newer generation trucks that the rake can be from 2-4" depending on where the truck is located, he said that all I should need are the UCA's, new keys, shock extensions and maybe a differential spacer kit. He told me to say my money on shocks since I only have 1300 miles on trucks, that the stock stocks would be Ok for awhile until I could say money for some Foxes or Bilsteins.

Damooch · September 24, 2018

On 9/19/2018 at 9:13 PM, Seapacer2 said:

Damooch,

You mentioned that you have a CCM level kit, what components are you utilizing on your 2017? I have a 2018 that I want to level, it has about 3-3.25" difference between the front and rear. I have sent a few emails out to different vendor and asked a few questions, I'm not sure if I can make up the difference by just cranking up the adjusting screws on my torsion bars, and I'm only going to be able to obtain about 2" from this, along with loosing ride quality. I have 18" OEM chrome wheels and the ultimate goat is also to get 285/70R18 size tires.

I’m using new upper control arms. Shock extenders and new torsion keys. Also got 2” blocks for rear. Wanted to keep the rake.