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-   -   33s and the 2.5" Rocky Road Spacer Lift (http://www.jeepgarage.org/f109/33s-and-the-2-5-rocky-road-spacer-lift-24722.html)

mhassler 06-21-2011 08:05 AM

33s and the 2.5" Rocky Road Spacer Lift
 
4 Attachment(s)
I went into NTB yesterday and they agreed to test fit some tires for me.

I had them install 275/70r18 Nitto Terra-Grappler's. Online tire calculator's indicate that this is a 33.16" x 10.83" tire. Nitto's website says it measures 33.27" x 10.94".

Anyway, here is what I took notice of along with a few pictures.

Up-front
I turned hard in each direction with no rubbing, perhaps when on the road and with the minimal body movement there could be minor rubbing on the felt. I was able to slide my pinky between the knuckle assembly and the tire so there should be no issues there.

Out-back
The front, inside portion of the tire just grazed the felt liner. You could see light on the inside rear.

This was all without the use of spacers on the stock 18" Jeep polished rims with a 56mm backspacing.


I feel that with the 2.5" RRO lift one would be able to install either 275/70r18 (33.16" x 10.83") or a 275/60r20 (32.99" x 10.83") tire as long as the true OD and width is as near those calculated numbers as possible. Remember, just because a tire is calculated as a certain size it may measure differently due to the tread, sidewall, etc.; this is evident in the case of the Nitto's.

Personally, I am looking at a BGF Rugged Terrain T/As which measure 33" x 10.90". I think the smaller 0.27" in true OD (.135" to each side) and slightly smaller width will provide the necessary clearance on the rear tire. And, I think the resultant sidewall bulge from upping to a 20" rim size with a shorter sidewall (as I plan to do) would be OK because the knuckle was nearer the tread ring and not the sidewall - I should have grabbed a pic of this.

I would not recommend the Terra-Grapplers in this size (275/70r18) as they are slightly larger than the calculated numbers and would rub in the rear - without the use of spacers.


There has been talk of adding a 285mm (11.22") section width tire (regardless of the width - obviously you need the lift for a 33) and after seeing this in person there is no way a 285mm section width tire in a 33" OD tire will fit on the stock rims (56mm backspace) with no spacers.
A 285mm section width in a 32" OD tire may fit utilizing the stock rims.
A 285mm section width in a 31" OD or smaller tire should fit using the stock rims.

I do not think a a tire over 33.25" OD in a 275mm (or greater) will fit without the use of a 1" or greater spacer/adapter, it would rub when turning and it would contact the knuckle assembly. A taller tire could possibly fit with if it were narrower (265mm or less).

Hope this helps in your consideration but you will need to do what you feel is best. I am still on the fence whether or not to order the 275/60r20s (33s). But then I think, if they rub at first I'll just have to wait a few thousand miles and they won't. But don't buy strictly because I said so - check for yourself.

4th Cherokee 06-21-2011 08:32 AM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
Great write up! What is your assement of the effect with the large tires and the quad drive and braking systems?

fljeepleo 06-22-2011 09:05 AM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
You have a picture of the whole rig from far away? I wanna see how those tires look from afar!

mhassler 06-22-2011 09:18 AM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
Quote:

Originally Posted by 4th Cherokee (Post 434856)
Great write up! What is your assement of the effect with the large tires and the quad drive and braking systems?

I am not sure I understand your question... what effect? What do you think will/would happen?

Larger tires will marginally throw off the speedo, which can be re-calibrated and it will slightly reduce MPGs do to the increased rotational mass. Changing your rear end gear ratio can help correct this. Also the increased vehicle height creates a bit more drag.

Quote:

Originally Posted by fljeepleo (Post 435620)
You have a picture of the whole rig from far away? I wanna see how those tires look from afar!

No, I don't. I used my iP4 so I couldn't get far enough away with the other vehicles in the work bay. And, I was taking quick pictures because they were nice enough to let me in to check the fit - I didn't want to be a nuisance to the others who were working.

Kangaroofarm 09-16-2011 11:12 PM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
Quote:

Originally Posted by mhassler (Post 434849)

I feel that with the 2.5" RRO lift one would be able to install either 275/70r18 (33.16" x 10.83") or a 275/60r20 (32.99" x 10.83") tire as long as the true OD and width is as near those calculated numbers as possible. Remember, just because a tire is calculated as a certain size it may measure differently due to the tread, sidewall, etc.; this is evident in the case of the Nitto's.

Personally, I am looking at a BGF Rugged Terrain T/As which measure 33" x 10.90". I think the smaller 0.27" in true OD (.135" to each side) and slightly smaller width will provide the necessary clearance on the rear tire. And, I think the resultant sidewall bulge from upping to a 20" rim size with a shorter sidewall (as I plan to do) would be OK because the knuckle was nearer the tread ring and not the sidewall - I should have grabbed a pic of this.

I would not recommend the Terra-Grapplers in this size (275/70r18) as they are slightly larger than the calculated numbers and would rub in the rear - without the use of spacers.


I do not think a a tire over 33.25" OD in a 275mm (or greater) will fit without the use of a 1" or greater spacer/adapter, it would rub when turning and it would contact the knuckle assembly. A taller tire could possibly fit with if it were narrower (265mm or less).

Hyourself.[/I]

Thinking of going the Rocky Road way myself soon! I also want to run 33's Nittos or Grabbers. I'm wondering, if I used a rim with 4.5-5 inches of back spacing ~ would that be enough to stop from rubbing? Currently looking at pro comps, and method race wheels like the ones on the Xplore Jeep. Thanks, for your input Awesome write up! :)

misantrop 09-29-2011 01:31 AM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
It does seem that rear tires are a bit tight. Should you place one on the rock to create some uneven load, and it looks like it will rub. But I guess slight trimming of inner fender will resolve the issue.

gmako74 12-06-2011 12:27 AM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
Did you purchase the upper control arms with the lift? I'm looking at purchasing the same kit myself. Thanks

JaxJeepGCL 01-29-2012 02:54 AM

Re: 33s and the 2.5" Rocky Road Spacer Lift
 
Just bought a RRO lift and plan on using Bilstein shocks and struts, but Im torn on tire size and tires in general, been looking at the BFG's KM2's according to some test results ROAD NOISE is just a lil different 7.7 to 7.9 from the MT to the AT, and that is one of my concerns, love the aggressiveness but hate the noise, also want to go with 33 10.50 instead of the 265-70-17....These will be attached to my Cragar Soft 8's...still in boxes!! I am ordering some spacers as well Any suggestions anybody? On tires and sizes...


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