Offset - Backspace - ideal fitment - Calculation chart - Jeep Garage - Jeep Forum

Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WK2 - > Suspension/Driveline/Brakes/Wheels/Tires

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #1  
Old 04-08-2016, 12:33 PM
Member
My Jeep: 2015 3.6L WK2
 
Join Date: Mar 2015
Location: Scottsdale
Posts: 605
Thanks: 98
Thanked 250 Times in 134 Posts
Rep Power: 15747
wk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond repute
Garage
Offset - Backspace - ideal fitment - Calculation chart

Ideal offsets for stock & lifted wk2s:
Stock 8" wheel = +56 offset
8" wheel +38 offset Moves wheel/tire combo out .70"
8.5"wheel +30 offset Moves wheel/tire combo out 1.25" (max ideal in my opinion) ((dont forget, wider tire pushes this further))
9"wheel +25 offset good luck, but semi aggressive
9.5"wheel +18 offset more aggressive

While im not the end all be all, Ive been in this game a LONG Time. Many years with Discount Tire and Discount Tire Direct and my own passion for vehicles, suspension and wheels/tires has helped me take a confusing situation and find ideal situations.

IDEAL fitment is largely based on opinion:
Do you want stance? (use a lower offset).
Are you lifted? (use a mid offset)
Like stock look (use high offset).

A good majority of this site likes to add larger tires. You can go as big as a 275/55-20 (or equal in 17 or 18") which is approx 32". On a stock wheel. Yes, you will clear the control arm bolt, no you will not rub.

for those that want to go 33... you gotta lift. 2.5 lift. IDEAL fitment, no rub, no pinch weld work etc is 8.5" wheel with a +30 offset. Chart below will show you conversions for 8, 9, 9.5" wheel. For example, on a 9"wide wheel that perfect 30 offset becomes 24-25mm. 9.5, it becomes +18. But, just because you have an equivilant offset doesnt mean that wider wheel wont end up rubbing (slightly). thats why I said the most IDEAL is 8.5 +30....because it is. Its the true, no rub, no mod 33" fitment.

Lowering your jeep is a different game. Depends on how much you lower it, what stance you go for, if you add in neg camber (please dont). From what I see on here, many go with a much wider wheel/tire combo when they drop. And thats fine too. I dont have any measurements handy but the best lowered look comes from bringing the wheel/tire combo almost flush to the fenderlip. when the suspension compresses on the road, the tire naturally goes in to neg camber and will tuck up inside the well nicely, if you arent too aggressive on the offset.

Its also important when tire shopping to get the actual specs from the tire manufacturer website. a 32" tire (by math) could be anywhere from 31.6-32.3 depending on who made it. when going to extreme fitments, its important to know this info.

in my last two WK2s ive run:
275/55-20 on stock wheels, stock height. Fits.
285/50-20 on stock wheels, stock height. Fits.
275/55-20 on 20x9 +18 wheels, Leveled. Slight rub up front, occasional rear bump on hard compression.
33x12.50-20 on 20x8.5 +31, full 2.5 lift. NO RUB, no need for pinch weld, no need for felt adjustment.
33x12.50-20 on 20x8.5 +31 2.5"lift PLUS 1/2" from Bilstein 5100s. youd think this would fit even better than the one above, untrue. Slight felt rub at this point on the front. The way the wheelwells are, they start to curve back towards the wheel at the bottom slightly (at least the lifted part of the felt), so after I added the 5100s to the 2.5 lift, i had very slight felt rubbing. Interesting, eh?

For those that run a 0, +12, +18 offset....yup, looks cool. Just be prepared for felt and pinch mods. No biggie, just a heads up. You also can/will touch your tire to the fenderlip when turning and under compression. If in high speed, slight cornering, under compression this could be bad. but few drive like this. Touching the lip while offroading slowly is no real big deal but could effect your overall up travel slightly.

Thats it for now. Feel free to ask away, but hopefully this post and the graph help you all a bit.
Attached Images
File Type: jpg wheel offset wk2project.jpg (274.2 KB, 338 views)

Reply With Quote
The Following 9 Users Say Thank You to wk2project For This Useful Post:
Sponsored Links
Advertisement
 
  #2  
Old 04-08-2016, 01:12 PM
Member
 
Join Date: Nov 2015
Posts: 81
Thanks: 0
Thanked 13 Times in 11 Posts
Rep Power: 542
DCROTHERS is on a distinguished road
Re: Offset - Backspace - ideal fitment - Calculation chart

That's awesome......Great summary and super helpful.
Thanks so much for bringing it all together!

Worthy of a STICKIE!
Reply With Quote
The Following User Says Thank You to DCROTHERS For This Useful Post:
  #3  
Old 04-08-2016, 01:22 PM
SilverBillet's Avatar
Senior Member
 
Join Date: Jan 2014
Posts: 2,009
Thanks: 2
Thanked 456 Times in 311 Posts
Rep Power: 32644
SilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond repute
Garage
Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by alludc View Post
A good majority of this site likes to add larger tires. You can go as big as a 275/55-20 (or equal in 17 or 18") which is approx 32". On a stock wheel. Yes, you will clear the control arm bolt, no you will not rub.

There are a good number of people who have tried the 275/55/20 and rub.
Many others don't. It's really hit or miss depending on the tire and suspension type. On the other hand ive never heard of 285/50/20 rubbing for anyone.

Great info otherwise.
Reply With Quote
  #4  
Old 04-08-2016, 01:28 PM
Member
My Jeep: 2015 3.6L WK2
 
Join Date: Mar 2015
Location: Scottsdale
Posts: 605
Thanks: 98
Thanked 250 Times in 134 Posts
Rep Power: 15747
wk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond repute
Garage
Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by MOFSTEEL View Post
There are a good number of people who have tried the 275/55/20 and rub.
Many others don't. It's really hit or miss depending on the tire and suspension type. On the other hand ive never heard of 285/50/20 rubbing for anyone.

this is why I mention in the long middle section about the importance of getting the actual tire spec from tire manufacturer website. in some cases, ive seen as much as a 0.8" difference in the same size tire, from different manufacturers. Ive personally tried 3 manufacturer 275/55-20s while at stock height and on stock wheels, all worked perfectly. However, if I made a 4th attempt with another company...it may have failed. But by and large, a 32" tire on stock tires on non air suspension should work all day
Reply With Quote
  #5  
Old 04-08-2016, 02:49 PM
GrandCherokee3270's Avatar
Member
My Jeep: 2014 WK2
 
Join Date: Feb 2016
Posts: 134
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 598
GrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond repute
Re: Offset - Backspace - ideal fitment - Calculation chart

One of the things to consider is the ability to tuck the tire either when flexing out or near full compression when driving hard. My 20's barely fit with 275/55. I didn't just get lucky I bought 34 mm offset rim designed for this vehicle. The SRT Replicas. It looks like it fits by mm and that's only when the tires are straight.
__________________
2014 WK2 Limited with 17" steel 40mm Offset wheels, Mastercraft Courser AXT C Load 275/70/17 Tires, Icon Coil Overs set to 2" with Tuff Country .25" Spacers on top, OME rear MD Coils and shocks.
Reply With Quote
  #6  
Old 04-08-2016, 02:54 PM
Member
My Jeep: 2015 3.6L WK2
 
Join Date: Mar 2015
Location: Scottsdale
Posts: 605
Thanks: 98
Thanked 250 Times in 134 Posts
Rep Power: 15747
wk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond repute
Garage
Re: Offset - Backspace - ideal fitment - Calculation chart

that is addressed also, in my post...
Reply With Quote
  #7  
Old 04-08-2016, 02:56 PM
Member
 
Join Date: Jan 2016
Posts: 375
Thanks: 139
Thanked 46 Times in 34 Posts
Rep Power: 859
FlyFinaticLou has disabled reputation
Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by alludc View Post
this is why I mention in the long middle section about the importance of getting the actual tire spec from tire manufacturer website. in some cases, ive seen as much as a 0.8" difference in the same size tire, from different manufacturers. Ive personally tried 3 manufacturer 275/55-20s while at stock height and on stock wheels, all worked perfectly. However, if I made a 4th attempt with another company...it may have failed. But by and large, a 32" tire on stock tires on non air suspension should work all day
ALLUDC, it's the "Fly" from 'Show & Tell' thread. Thanks for the great videos there & elsewhere ! My Question, specific to my SOON to order 2016 75th G.C. Laredo E, with ORA1 (& maybe tow IF it doesn't alter the breaks to HD, which others here have said will not allow me to go to a 17" OEM wheel ? Odd because the Original wheel on the Laredo IS a 17" thus my confusion persists ?).

JEEP switched things up on these 75th-ers by going to an 18" on the Laredo version (20" on Limited). Come hell or high water, I am gonna get these 18" wheels with the tire they Option on the Limited 75th - Goodyear AT Adventure w/Kevlar. I like these cause I had the previous iteration, SilentArmor
w/kevlar. The AT's are a bit more "aggressive" probably a bit "harsher" ON road but I won't mind. These AT's have an OD of 30'5" (OE std.) and
are 265/60R18 (OE std.). This same tire in a 65 side brings the OD to 31.1".
Would that be "pushing it" as far as off roading or for that matter on road ?
I think the answer is obvious / yes ? Don't have the $$$ to experiment nor can I afford to "change-up" the suspension or do ANY kind of "lift" - perhaps spacers in the future, but . . . ?

Trying to get answers out of JEEP "Contact Us" is Total waste & aggravating (the guy is . . . dumb ?) Was looking for the answer to the 17" wheel that comes on the 75th version of WRANGERS - because it has similar style & the bronze color. I'm thinking ok 17" - the Original OD of the G.C. Laredo's . . . WILL IT FIT ? Of course I do not know the specs of that wheel to know it it will Properly Fit around the Breaks of 'my' G.C. ? Bottom line would be the added off road ability because of the "sides" going to 70 or perhaps 75 IF Fit ?

ALLUDC, . . . GOT ANY FRIENDS WHO KNOW OR CAN COME UP WITH A DEFINITIVE ANSWER ON THE 17" rim fit ? ? ? Will be ordering by end of this month & if I had the knowledge I could use it to maybe get the dealer to do a swap or worse case, Later (~ 1 yr. ) spend some cash !
Thanks, very much. FlyFinaticLou
Reply With Quote
  #8  
Old 04-08-2016, 03:16 PM
SilverBillet's Avatar
Senior Member
 
Join Date: Jan 2014
Posts: 2,009
Thanks: 2
Thanked 456 Times in 311 Posts
Rep Power: 32644
SilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond reputeSilverBillet has a reputation beyond repute
Garage
Re: Offset - Backspace - ideal fitment - Calculation chart

Anyone have a fly swatter?
Reply With Quote
  #9  
Old 04-08-2016, 03:31 PM
Member
My Jeep: 2015 3.6L WK2
 
Join Date: Mar 2015
Location: Scottsdale
Posts: 605
Thanks: 98
Thanked 250 Times in 134 Posts
Rep Power: 15747
wk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond reputewk2project has a reputation beyond repute
Garage
Re: Offset - Backspace - ideal fitment - Calculation chart

Low, according to posted specs at FCA media, 15-16 models show only two options up front for non srt gcs. 13.0 and 13.8. 13.0 on v6, and 13.8 on ecodiesel and hemi. rears are the same.

I see no mention of any other significance. if you have 13.0s, 17s will go. if you have 13.8, nope.
Reply With Quote
  #10  
Old 04-08-2016, 03:34 PM
GrandCherokee3270's Avatar
Member
My Jeep: 2014 WK2
 
Join Date: Feb 2016
Posts: 134
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 598
GrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond reputeGrandCherokee3270 has a reputation beyond repute
Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by alludc View Post
that is addressed also, in my post...
Yes you did, I didn't read the bottom. However you state that may be an issue for 0-18mm I think you said but again I have 34mm offset and it fits by mms. I also had to bend back a couple pieces of metal where pins go to hold the felt. They didn't stick out much but the tire was definitely hitting them.

I'm still dying to see pics of you flexing out and stuffing those tires like you said you could.
__________________
2014 WK2 Limited with 17" steel 40mm Offset wheels, Mastercraft Courser AXT C Load 275/70/17 Tires, Icon Coil Overs set to 2" with Tuff Country .25" Spacers on top, OME rear MD Coils and shocks.
Reply With Quote
  #11  
Old 04-09-2016, 09:50 PM
Member
 
Join Date: Jan 2016
Posts: 61
Thanks: 3
Thanked 4 Times in 3 Posts
Rep Power: 470
VWTG is on a distinguished road
Re: Offset - Backspace - ideal fitment - Calculation chart

Awesome Deal. Your jeep has inspired me.
Stock 20" Altitude wheels. Can I fit the 33x12.5x20
RRO 2.5"Lift
Atturo Trail Blade XT with 1" spacer
Reply With Quote
  #12  
Old 04-09-2016, 11:53 PM
Member
 
Join Date: Mar 2016
Posts: 72
Thanks: 15
Thanked 9 Times in 8 Posts
Rep Power: 410
ILLSMOQ is on a distinguished road
Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by VWTG View Post
Awesome Deal. Your jeep has inspired me.
Stock 20" Altitude wheels. Can I fit the 33x12.5x20
RRO 2.5"Lift
Atturo Trail Blade XT with 1" spacer
That would be equate to about a +31.5 offset on that 8" wheel...it will work but it might rub the felt and the pinch weld. If you wheel it, you may have some issues. If a 3/4" spacer (equals +37 on your 8" wheel) is possible it would be better...and get you closer to ALLUDC's spec.

Also on your 8 inch wheel it will be sucked in quite a bit...though that might get you done clearance haha...

My 33x12.50x20's are sucked in a bit on a 9" wheel. Might be a bit much to try and fit it on an 8"...it can be done but might look funny...maybe not depending on the tire though.

If you can't afford wheels I'd try it.

Also I'd get the 3/8" trim spacers from rocky road road too for a little bit more up front.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hemi Gas Mileage calculation TheNoachSHO Engine Performance/Intake/Exhaust 3 12-19-2014 06:32 PM
Minimum ideal build date for 2014? Jeep_GC 2014+ Jeep Grand Cherokee Ecodiesel 3.0 7 09-21-2014 05:53 AM
Offset & Backspace - How Do They Relate? Discount Tire Wheels and Tires 0 03-05-2012 12:07 PM
Ideal tire size for 4.56 gears? Kev- Wrangler-YJ, TJ & JK 2 11-03-2011 01:41 PM
Ideal road for a WK2 road test? Milous Grand Cherokee - WK2 - 8 06-24-2010 03:28 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 10:55 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community

JeepGarage.org is in no way associated with or endorsed by FCA US LLC. Chrysler, Dodge, Jeep, Ram, Mopar and SRT are registered trademarks of FCA US LLC.