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  #13  
Old 04-10-2016, 01:15 AM
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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

I wouldn't go any less than 8.5 width, with this 33x12.50.

I think that it "could" work...just not something personally I'd do. Honestly, iD be happier on a 9" wheel with this tire.

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  #14  
Old 04-10-2016, 08:50 AM
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Re: Offset - Backspace - ideal fitment - Calculation chart

Understood. Not about the money although it always plays a part. I like the wheels.
A quick comparison.
33x12.5x20 dia. 32.8 w 12..5
285/55R20 dia. 32.6. w 11.5
couple of questions.
Why make tires so close in spec to each other?
Did I just eliminate need for any spacer?
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Old 04-10-2016, 10:11 AM
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Re: Offset - Backspace - ideal fitment - Calculation chart

the 11.5 vs 12.5 is not just a standard inch. This is a measurement of the tires width when aired properly on and ideal width rim. Which would be 9.5 to 10.5

also, we're still needing to move the wheel outwards, otherwise you will run into the issue of rubbing (in this case sitting on) the upper control arm bolt. Not just because of width alone, but also increased height.

A 275/55-20 (32.1)on stock wheel without a spacer will work and will clear this bolt by 2 or 3mm.

The spacer (or appropriate offset) is also needed to get the tire placement correct so that when you turn, the tire has room to fit properly in the wheel well and avoid rubbing on the felt, the pinch weld and the lower front plastics. There's alot to this, when it comes to going so much bigger than stock.

32s are eassssssy. 33s take measurement and finesse
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Old 04-10-2016, 11:28 AM
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Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by VWTG View Post
Understood. Not about the money although it always plays a part. I like the wheels.
A quick comparison.
33x12.5x20 dia. 32.8 w 12..5
285/55R20 dia. 32.6. w 11.5
couple of questions.
Why make tires so close in spec to each other?
Did I just eliminate need for any spacer?
Yeah, the five spokes are nice, just too narrow but if you like the wheels then give it a shot...the tire being a bit too wide for the rim might not bother you once it's installed, might look okay depending on the brand of tire. Worst case, you don't like it and then you buy a set of wheels that will fit right.

Also, actual tire sizes differ from brand to brand even though the size designation is the same.

Example: I ordered two sets of tires. Toyo Open Country MT and Fuel Mud Gripper M/T, both in 33x12.50x20.

Stacked next to each other the Toyo stack was 1.5" taller than the Fuel stack. I ended up going with the Fuel tires because of the slightly smaller actual size.

Sometimes going to an All Terrain from a Mud Terrain will give a bit more clearance too.
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  #17  
Old 04-10-2016, 10:41 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

I'll be following this thread and asking for some opinions as well. I purchased a set of the 5 hole JK Sahara wheels off Craigslist for a song. Upon mounting them I noted that they hit the calipers up front every so slightly. I purchased a set of BORA 1.25 inch spacers that are supposed to be here tomorrow, as I didn't want to cut the studs. When I mocked up the wheel with an approximate 1.25 inches I noted that the wheels are about even and might even stick a little out beyond the outer edge of the top of the plastic fender flare. Once the spacers are here, and can mount them, and I'll know exactly where I'm at. I have Bilstein's up front set at 1.75 and the Jeep sits level now. I was planning on 275 65 18 Duratracs, but with the wheels out as far as they are, I'm afraid of possibly hitting the fender flares or pinch weld when off road and the tire is turned. The tires will definitely stick out beyond the fender flares though as the Sahara wheel is only 7.5 inches wide. I was planning on adding a trim packer and a spacer of some sort out back eventually. I know that RRO will sell their spacer and shock extension from their 2.5 lift, but I'm almost afraid it'll be too much and I have that jacked up in the rear look.
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  #18  
Old 04-10-2016, 11:38 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

Vmx that's a 17x7.5 +44 wheel. Adding a 1.25 spacer makes it effectively a 12.5 offset. If it were an 8.5 rim that would make the offset approx 24 or 25 so it's close to a good fitment but it's leaning towards the end of that fit. Will you still clear with just a 1" spacer? That'd put you in overall better shape.

the 275 65 18 is only mild. 32.1. If you rub at all it should be very minor and easily corrected. I don't have experience with just the 1.75 lift, but I think you're only going to see a bit of felt rubbing on that setup
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Old 04-11-2016, 10:41 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

Well spacers came in today and its not as bad as I had feared. The wheels are at least completely under the top of the fender flares when under the jack. My biggest fear was that they were going to stick out like some hoopty from the ghetto. I understand though that the tires will probably stick out beyond the fender flares a tad, and I'm okay with that. I measured and probably could have gotten away with 1 inch spacers on these wheels although it would have been very close. The wheels have an indent of approximately 1/2 inch for the studs to fit in. I will certainly speak to the quality of the BORA spacers though. They fit onto the hub and into the wheels very tightly, so they shouldn't be an issue, but I haven't driven with them on yet. I'm certainly not an expert on wheels and tire sizes, especially on this Jeep. What does everyone else think of this setup? Should I go with it, or try something else?

I'm going to powdercoat the wheels gloss black once I get the whole spacer thing figured out.

20160411_193345.jpg

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Old 04-11-2016, 10:56 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

When the suspension compresses they will probably push out a little more. I bet it will look good.
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  #21  
Old 04-12-2016, 11:01 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

This is good stuff. Had 275 55 20 BFG Rugged Terrain on my 2011 with no issues. Looking at Duratracs for my 2014 - just trying to decide between the oversize 20's or go down to 18's
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Old 04-13-2016, 06:36 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by alludc View Post
the 11.5 vs 12.5 is not just a standard inch. This is a measurement of the tires width when aired properly on and ideal width rim. Which would be 9.5 to 10.5

also, we're still needing to move the wheel outwards, otherwise you will run into the issue of rubbing (in this case sitting on) the upper control arm bolt. Not just because of width alone, but also increased height.

A 275/55-20 (32.1)on stock wheel without a spacer will work and will clear this bolt by 2 or 3mm.

The spacer (or appropriate offset) is also needed to get the tire placement correct so that when you turn, the tire has room to fit properly in the wheel well and avoid rubbing on the felt, the pinch weld and the lower front plastics. There's alot to this, when it comes to going so much bigger than stock.

32s are eassssssy. 33s take measurement and finesse
Completely understand. So in an attempt to dig deeper and figure this out. I go to the black rhino website use the fitment calculator and they have an option for grand cherokee(lifted) the only offset available is
- 12. Why so off your +30.
With stock wheels at +56 and ideal being +30
Then if the Atturo trail blade XT 285/55-r20 rated for 8-10 wheel.
1" space would bring offset to approx ideal?
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  #23  
Old 04-13-2016, 06:53 PM
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Re: Offset - Backspace - ideal fitment - Calculation chart

Quote:
Originally Posted by VWTG View Post
Completely understand. So in an attempt to dig deeper and figure this out. I go to the black rhino website use the fitment calculator and they have an option for grand cherokee(lifted) the only offset available is
- 12. Why so off your +30.
With stock wheels at +56 and ideal being +30
Then if the Atturo trail blade XT 285/55-r20 rated for 8-10 wheel.
1" space would bring offset to approx ideal?

I have asked them to correct that.
** a -12 offset will fit a lifted grand cherokee. hell, itll fit a regular one. Doesnt mean its right. It also doesnt say with what size tire. Assume they mean, their 20x9 with a -12 on a stock 265/50-20 tire will work. It probably does. Unfortunately, i think they just copied that over from Wrangler fitments. poor choice.

the 285/55 is 32.6 I would have to know what wheel width you are looking at to be able to tell you what to do for offset. if the wheel you want is 20x8.5 +31, you are right on the money. if its a 20x9 you want a +25 offset is closer to ideal.

sorry if im not answering what you asked, your last sentence is a bit confusing
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  #24  
Old 04-13-2016, 09:14 PM
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Offset - Backspace - ideal fitment - Calculation chart

I have an 11 Overland with the quadra lift. I have the Llyms module on it. It gives 1.25" or 2" of extra lift depending on the setting. I am wanting to run a 275 70 18 tire on a wheel with +34 offset. I don't mind trimming the felt, bolt or pinch welds. The truck won't be taken off-road with this setup. I plan on something closer to stock for that. The tire is basically a 33.2x10.8". Any thoughts or pics would be great. Thanks.
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