Tire upgrade / upsize question

[summitx]

Looking to upsize the tires / wheels on my 09 GMC Dirtymax. Want to go to an 18" wheel with 285/65/18 tires. Does anyone know if they will fit on the Duramax without at least a level kit? Right now it's sitting stock with 17" wheels.

 

[AreWeThereYet]

IIRC the biggest you can go on factory rims and a 2" front level is a 285 70 17 or you will rub, you will have to match the backspacing on the factory rims with the new 18's.

 

[summitx]

I'm lost, the rims I am looking at are a set of Moto metal 18's that came off of a dodge 3500. When it comes to backspacing and stuff I really am lost, never really paid much attention to try and figure it out. Anyone want to help with an edumacation? would the 285/65/18 be equal in size to the 285/70/17 given the larger wheel diameter and different tire profile?

 

[E to the v]

They ll be really close

 

[AreWeThereYet]

The 285 70 17 will be .25" taller,.. other specs pretty much bang on.

285 70 17 32.7" tall
285 65 18 32.5" tall

Mounted and installed on truck you will be about 32" tall,.. my 295 70 17's are 32.6" tall mounted on truck.

 

[summitx]

OK So I'm not that out to lunch, now the question is will they fit without the level kit? I don't have it installed yet and I have to get rid of these stock hocky pucks. They are brutal on anything but dry pavement

 

[grizzlymud]

It will also depend on the tire, not all are the same. There are a couple of backspace charts online that will help.

 

[Stg2Suby]

I have 285/70/17 on stock rims 2009 Dmax they rub significantly even with torsion bars raised about 1.5" over stock. I cannot turn full lock and the lugs have already ripped out a plastic rivet and damaged the inner fender plastic.

Note you don't necessarily need a levelling "kit" with any parts to increase the front ride height, there is a preload bolt on the torsion bar mounts under the cab that you turn to adjust the height. Maybe you need keys if you want to crank the bars right up to maybe 3" but then the ride gets choppy apparently.

My truck is at the body shop right now hopefully getting a solution to the rubbing which involves some cutting and pounding the sheetmetal at the rear of the front fender to make room where the tire rubs. Google "small fender mod" and you should find the info how to do this mod.

Good luck this wheelwell clearance problem is a PITA and why you see so many late model GM/Chevs' with a 4" lift.

 

[AreWeThereYet]

My buddies '09 maxi truck up the street has a 2" level with 285 70 17 and it looks stellar. Also you will stiffen up the front suspension by using your torsion arms to lift,.. get lift keys and retain your soft ride and lift to boot.

 

[grizzlymud]

Actually changing the keys is the same as cranking them only you can go further, the new keys are just indexed different.

 

[kykissurplus]

Hey guys...i got a 2010 isuzu dmax..just wondering how i can fit 295/65/R20 tires on it..i need suggestions on the lift..

 

[KawisakiRider]

My buddies '09 maxi truck up the street has a 2" level with 285 70 17 and it looks stellar. Also you will stiffen up the front suspension by using your torsion arms to lift,.. get lift keys and retain your soft ride and lift to boot.

I have the new keys so I could fit 285/70/R18 on my 2008 and they fit fine and look really nice but the ride is no better than when I used the factory keys to fit 285/75/17, very stiff, like riding in a Dodge/Ford.

 

[rondun]

On my 2010 Chev 1500 4wd, I have 265-65-18 that is all that will fit. At times backing out of my driveway they will rub. I did try 275-70-18 NO WAY RUBBED. I put a 2in leveling kit no more rubbing, But I had to install a extra leaf in the rear. Looks good now and ride never changed.