Biggest tire for lifted trailblazer and wheel spacers question

zombiexsoldier

Original poster
Member
May 30, 2013
42
I have a 2007 4wd trailblazer. I have a truxxx lift kit installed on it which is a suspension lift for 2.5inch in the front 1.25 in the rear. It sit perty much leveled. I am about to get 1.5inch wheel spacers installed and I just would like to know if I can fit 265/70/17 tire on stock rims. The tire I have been looking at is general grabbers at2. Please help
 
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tbyoda

Member
Apr 19, 2013
187
zombiexsoldier said:
I have a 2007 4wd trailblazer. I have a truxxx lift kit installed on it which is a body lift for 2.5inch in the front 1.25 in the rear. It sit perty much leveled. I am about to get 1.5inch wheel spacers installed and I just would like to know if I can fit 265/70/17 tire on stock rims. The tire I have been looking at is general grabbers at2. Please help

Please take look at this thread, a lot of good data. OffRoad TB - View topic - Lift/Tire Size Chart

Max tire size dictated by the gearing for example 3.42 gears = max tire is 32" the 265/70R17 is 31.61" so with a 2.5" body lift and spacers you should be good with any fender cutting but look over the thread.

Offroadtb.com Tire Size Calculator

Offroadtb.com Gear Ratio Calculator
 
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The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Welcome! Just for posterity, the Truxxx spacer kit is a suspension, not a body, lift.
 

zombiexsoldier

Original poster
Member
May 30, 2013
42
the roadie said:
Welcome! Just for posterity, the Truxxx spacer kit is a suspension, not a body, lift.

o I seen you a lot on trailvoy but I don't think people use that anymore but would you know what this biggest tire I could fit?
 

c bausch

Member
Jan 13, 2012
183
Well i had a 2.5 " lift with 285's a little fender plastic trim and they fit good . My profile picture is w/ the wheels and lift
 
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HARDTRAILZ

Moderator
Nov 18, 2011
49,665
265s rubbed with my 2.5 inch lift...

there is a ton of info available if you search. I believe evan a few charts of what fit and doesn't. Maybe even chart of who is running what.
 

Pittdawg

Member
Dec 5, 2011
538
zombiexsoldier said:
I have a 2007 4wd trailblazer. I have a truxxx lift kit installed on it which is a suspension lift for 2.5inch in the front 1.25 in the rear. It sit perty much leveled. I am about to get 1.5inch wheel spacers installed and I just would like to know if I can fit 265/70/17 tire on stock rims. The tire I have been looking at is general grabbers at2. Please help

Roadie...correct me if I'm wrong but I seem to recall you posting awhile back a lift does nothing to change the proximity of the ball joint to the width of the tire correct? I.e., a lift may help with vertical clearance but in terms of going to a 265 or wider tire the lift does nothing?
 

Short Bus

Member
Dec 2, 2011
1,906
I have Mark's 2.5" kit and run 265/70/17s
 

The_Roadie

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Nov 19, 2011
9,957
Portland, OR
Pittdawg said:
Roadie...correct me if I'm wrong but I seem to recall you posting awhile back a lift does nothing to change the proximity of the ball joint to the width of the tire correct? I.e., a lift may help with vertical clearance but in terms of going to a 265 or wider tire the lift does nothing?
That's the dirty little secret. :thumbsup: The challenge of the upper ball joint location is entirely defined by the steering knuckle design. A lift helps you not rub a larger tire on the fender well lining, but when you get over 30.5" diameter, the upper ball joint overhang is the ultimate restriction. Everybody contemplating larger tires needs to spend ten minutes looking the suspension over and understanding what dimensions change when it cycles up and down. The ball joint to corner of the tire dimension is defined entirely by the steering knuckle design. Wider and larger tires on the OEM rim will push the outer edge of the tire out and up, but the inner edge will go in and up. And that's where the ball joint lives.

Aftermarket rims can push the entire tire outwards, but you have to do the backspacing math to see if it will hit. :yes: Or put one on and try it if the math is too hard. :lipsrsealed:
 

Darkrider_LS

Member
Jan 25, 2013
9,332
This much i have learned thus far from reading on both here and ortb. Max you can clear in stock config is 30.5-30.6 depending on tire. (Wrangler silent armors are 30.6 and i have seen them on stock TBs a few times now). Using Marks spacers on stock Full size or TB rims depending on which bolt pattern you go with gives you a 4.5 back space allowing a taller tire to be fitted to the TB. If im not mistaken this allows a 31" on a 2" lift and a 32" on a 2.5 and from the sounds of it around a 33" on a 3" lift. Gearing being your ultimate limitation. Here is a chart i found on another forum when i was asking what max tire size can be ran on what gearing on my full size truck.

Note: this is not the original, just an edited version showing ideal for what gearing from the looks of it.

On the chart...
Yellow means better fuel economy
Green is stock like gearing
Red is better suited to offroad conditions
 

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Pittdawg

Member
Dec 5, 2011
538
That's why I need Shortbus to respond. He indicates he has a 31.7 diameter tire with a lift but makes no mention of wheels spacers.
 

Short Bus

Member
Dec 2, 2011
1,906
Pittdawg said:
With no wheel spacers?

I have Mark's 1.5" wheel spacers, before that I had 265/65/17s without spacers or a lift.
 

Pittdawg

Member
Dec 5, 2011
538
Short Bus said:
before that I had 265/65/17s without spacers or a lift.

That's what I'm running now. Wouldn't mind a small lift up front but don't want to go to spacers.
 

Jimmyz

Member
Jul 3, 2013
22
Sorry but I'm new to this site. Who is Mark, and where can I buy some of his 1 1/2" wheel spacers?
 

Jimmyz

Member
Jul 3, 2013
22

Short Bus

Member
Dec 2, 2011
1,906
Jimmyz said:
First thing I'd doing is replacing all the shocks. Bought some Monroe Sensa-Trac Quick Struts for the front and Sensa-Trac for the rear.

Will probably add a 1 1/2" spacer in the front to level it out some. Truck has a lot of rake to it.

Hopefully if I can get the money together I'm planning on a set of wheel adopter and a set of 17" Chrome Escalade wheel with GMC center caps. (I already have the wheels)

Jimmyz said:
OK, is he the guy that sells the wheel spacer to forum members for something like $169.00 ?

The Wheel spacer aren't for lift (you need strut spacers for that), they push your wheels out so bigger tires won't hit/rub the ball joint that the engineers at GM put directly over the tire.
 

Jimmyz

Member
Jul 3, 2013
22
Short Bus said:
The Wheel spacer aren't for lift (you need strut spacers for that), they push your wheels out so bigger tires won't hit/rub the ball joint that the engineers at GM put directly over the tire.

Yes I know that. Need them for the Escalade wheels
 

zombiexsoldier

Original poster
Member
May 30, 2013
42
zombiexsoldier said:
I have a 2007 4wd trailblazer. I have a truxxx lift kit installed on it which is a suspension lift for 2.5inch in the front 1.25 in the rear. It sit perty much leveled. I am about to get 1.5inch wheel spacers installed and I just would like to know if I can fit 265/70/17 tire on stock rims. The tire I have been looking at is general grabbers at2. Please help

I now have the tires and they fit with minimal trimming
View attachment 30489
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zombiexsoldier

Original poster
Member
May 30, 2013
42
Pittdawg said:
This must be without spacers? I can't imagine you need to trim with a lift and spacers?

this is with 1.5inch spacers and suspension lift there was minimal trimming the guy said who put it on for me he didnt charge me for trimming cause he only had to do slight trimming he said
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Pittdawg said:
This must be without spacers? I can't imagine you need to trim with a lift and spacers?

I had to w suspension only lift n spacers to fit 265s.
 

djthumper

Administrator
Nov 20, 2011
14,950
North Las Vegas
Sure it will fit. The largest tire size is still 30.5".
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
If the offset of the 18x8 is right, it may fit larger than 30.5 actually. We really would need more data to recommend a tire size.
 

paul2005tb

Member
Nov 26, 2014
299
Massachusetts
I have a 3in body lift and a 3in suspension lift. I have Marks wheel spacers too. The only limitation I have is my 3.73 rear gear. Even though I drive like an old lady and never tow anything Im going to keep my tire diameter below 33.8. Im looking at 285/70/17 or 295/70/17 or 255/80/17.
 
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paul2005tb

Member
Nov 26, 2014
299
Massachusetts
took a careful look up on that "chart of all charts" showing what tires folks with 6in lift and spacers are able to use. I did not see a match for my case. If you have a 6in lift (3in suspension, 3in body = 3+3 lift) and you have MarkMC wheel spacers can you tell me if you are running 33in or 34in tires and what width are you running. Id like to know if I can get up to 33/10, 33/11 or 33/12 without cutting any metal. My measurements suggest I can get 33/10 but that 33/12 will be too close with the upper ball joint even with the spacers and will very nearly interfer with the metal aft of the front wheels when the wheel turns. Well these are my deductions based on a tape measure.

If you have greater than a 32.7in tire on a 3+3 lift with wheel spacers without any cutting of metal please tell me what you have.
 
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paul2005tb

Member
Nov 26, 2014
299
Massachusetts
The chart is incredibly helpful but the word "trim" can mean so many different things, it would be great if the build notes gave more details for each of the specific cases.

For instance, I have (MarkMC) 3in body lift + 3in suspension lift + 1.5in spacers. My target tire/wheel is 33x11 with a zero offset rim.

I want to put 33x11 on the truck (I have the 3.73 gear and I have an auxillary trans cooler but I dont really tow anything) .

I have figured out that the 33x11 would fit if I were planning on using the OEM wheel offset but figuring out the clearance with a zero offset wheel (effectively a loss of almost 2inches of positive offset).

Assuming zero-offset wheels then some careful calculations are needed to determine the interference that results behind the front wheels:

So here is my best shot :
tire diamter D=diameter
tire width W

1) first measure your total diagonal length of tire (this is the distance from the centered pivot point to the far edge of the tread :

d= sqrt((D/2)^2 + W^2)

this tells you the total wheel well space necessary from the center of the hub turning/pivot point. This is the sweep necessary for the tire.

2) now get in car and turn steering so that you turn tire and see how much clearance you have with that present d. Any extra space that you have there tells how much space in the wheel well you have to work with.

So now I need to make a good approximation of the added sweep that additional offset will cause, so

3) now calculate your new effective tire d with the new offset wheel Wn=W+Offset

4) Calculate your new effective tire diagonal
dn= sqrt( (Dn/2)^2 + Wn^2)

now if the extra space from 2) does not exceed the difference dn-d then that offset is not going to work.

This is only a rough approximation. It assumes that the pivot point is inboard at the back of the rim. That is not a bad approximation but it is not perfect either.
 
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wstuckey1

Member
Apr 11, 2018
457
Fenton MI
The chart is incredibly helpful but the word "trim" can mean so many different things, it would be great if the build notes gave more details for each of the specific cases.

For instance, I have (MarkMC) 3in body lift + 3in suspension lift + 1.5in spacers. My target tire/wheel is 33x11 with a zero offset rim.

I want to put 33x11 on the truck (I have the 3.73 gear and I have an auxillary trans cooler but I dont really tow anything) .

I have figured out that the 33x11 would fit if I were planning on using the OEM wheel offset but figuring out the clearance with a zero offset wheel (effectively a loss of almost 2inches of positive offset).

Assuming zero-offset wheels then some careful calculations are needed to determine the interference that results behind the front wheels:

So here is my best shot :
tire diamter D=diameter
tire width W

1) first measure your total diagonal length of tire (this is the distance from the centered pivot point to the far edge of the tread :

d= sqrt((D/2)^2 + W^2)

this tells you the total wheel well space necessary from the center of the hub turning/pivot point. This is the sweep necessary for the tire.

2) now get in car and turn steering so that you turn tire and see how much clearance you have with that present d. Any extra space that you have there tells how much space in the wheel well you have to work with.

So now I need to make a good approximation of the added sweep that additional offset will cause, so

3) now calculate your new effective tire d with the new offset wheel Wn=W+Offset

4) Calculate your new effective tire diagonal
dn= sqrt( (Dn/2)^2 + Wn^2)

now if the extra space from 2) does not exceed the difference dn-d then that offset is not going to work.

This is only a rough approximation. It assumes that the pivot point is inboard at the back of the rim. That is not a bad approximation but it is not perfect either.
You made me feel like I was sitting in Calc 2 again. Felt like you were going to tell me to integrate it and see if x tire with y backspacing would fit. lol
 

paul2005tb

Member
Nov 26, 2014
299
Massachusetts
If anyone has a 33x11 (285/75/16) on our platform (with 3in suspension lift and 3in body lift) can you please tell me your total net offset and exactly what trimming you had to do to the fender behind the front wheel wells.

I trust my calculations up to a point but I do not want to cut any fender metal.

If the chart is accurate, there would seem to be almost no evidence that a body lift is of any value in increasing tire size.
 
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