Will I have issues with tire clearance?

[Bubblehead]

Hi, new to this forum. I have a 2006 TJ Unlimited with a 4” suspension lift. Currently running 33”x12.5x15 with a -20 offset wheel (no clearance issues currently) but would like to run 33”x10.5x15’s on the stock Ravine wheels. Any issues I may encounter? Thanks

 

[fuse]

Welcome!

I had issues with 31x10.5R15 tires on Ravine wheels hitting the front spring perch at anything close to full steering lock and full compression of the suspension. For my smaller tires, adjusting the steering stops and adding a little bump stop is enough to deal with it. With bigger tires, you may have other issues, and the best way to tell is to fully cycle the suspension and steering (i.e. do a bump stop check).

How much additional bump stop do you have? Can you post pics of the current suspension setup?

 

[Jay P]

I’m putting my 33x12.50s on Ravines. The issue is backspacing which if 5.5” for Ravines. You may need wheel adapter/spacers with 10.50 but maybe not. I can’t even get my ravines on with 12.50 because the tires hit the frame and there’s only a thread or 2 showing though on the studs.


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[Mr. Bills]

#1 - Start thinking backspace rather than offset. Backspacing is the measurement between the wheel mounting surface on the wheel and the inside lip of the wheel. The problem with using "offset" is that the value changes with wheel width whereas backspacing is a constant. For example, The offset for a 15x8 wheel with 4" backspacing would be -12mm; the offset for a 15x10" wheel with the same 4" backspacing would be -38mm.

#2 - For 33x12.50 and 35x12.50 tires you will want from 3.6" to no more than 4.5" backspacing on 8-10" wide wheels. However, 4.5" backspacing will most likely rub and will require the addition of at least one washer under each steering stop and 3.6" will stick out farther and may result in the dreaded "skateboard" look.

#3 - My preference is 4" backspacing for a 12.5" wide tire on an 8"-10" wide wheel. However, even 4" backspacing may require a washer under the steering stops depending upon whether the particular tire is "wide for its size," i.e., the industry average for 33x12.50 or 35x12.50 may be a 12.5" section width but some brands are a bit fatter, sometimes even 13".

#4 - If I recall correctly the factory Ravine wheels are 15"x8" with 25.4mm offset and 5.5" backspacing. You would need to run spacers 1.25" or 1.50" thick to make them work.

If you would like to visualize the effect of changing tire size, wheel width, offset ,and backspacing this calculator can be quite illuminating: https://www.rimsntires.com/specspro.jsp

 

[Jerry Bransford]

What wheels are you wanting to use and what width, 7" or 8", are they? I need the width to be able to convert that useless -20mm offset measurement to the wheel's backspace dimension which is far more useful for Jeep and truck wheels.

Offset is a measurement that is only useful for car wheels, forget you ever heard it where Jeep wheels are concerned. Offset and backspace are not interchangeable terms, they measure two different dimensions.

 

[Jay P]

The Ravines are 15x8 and they look fantastic in my opinion.

First pic I stole. Second pic is my spare.
I live in SLC and I’m waiting until spring to make the switch.


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[bobthetj03]

1.25" spacers and 2" bumpstop extension should make them work. You'll rub the front tires on the factory sway bar just a wee bit at full stuff/full lock. add a washer to the steering stops to cure that.

 

[fuse]

What wheels are you wanting to use and what width, 7" or 8", are they?

I think the OP said 33x10.50R15 on Ravine wheels, which are 15x8 with 5.5" backspace.

Looks like some of the responses have been for 33x12.50R15 tires instead of the 10.50 tires the OP asked about.

 

[Jerry Bransford]

I think the OP said 33x10.50R15 on Ravine wheels, which are 15x8 with 5.5" backspace.

Yes he did but not the -20mm offset dimension he mentioned, that's why I asked him for more information on his wheels. A -20mm Offset on an 8" wide wheel converts to 3.71" of backspacing which never came on a factory wheel.

 

[Mr. Bills]

I think the OP said 33x10.50R15 on Ravine wheels, which are 15x8 with 5.5" backspace.

Looks like some of the responses have been for 33x12.50R15 tires instead of the 10.50 tires the OP asked about.

No Problem.

For @Bubblehead with his 33x10.5 tires, I recommend that he run 1.0" spacers with his 15x8 5.5" backspace Ravine wheels to net 4.5" effective backspacing, available here: https://www.titanwheelaccessories.c..._wrangler~sz_wheel-spacers~yj_1-wheel-spacers He could also run 1.25" spacers to net 4.25" effective backspacing.

For @Jay P with his 33x12.5 tires, I recommend that he run 1.5" spacers with his 15x8 5.5" backspace Ravine wheels to net 4.0" effective backspacing, available here: https://www.titanwheelaccessories.c...rangler~sz_wheel-spacers~yj_1-5-wheel-spacers He could also run 1.75" spacers to net 3.75" effective backspacing.

 

[fuse]

Yes he did but not the -20mm offset dimension he mentioned, that's why I asked him for more information on his wheels. A -20mm Offset on an 8" wide wheel converts to 3.71" of backspacing which never came on a factory wheel.

Maybe I'm reading into it, but it sounded to me like the OP was switching wheels at the same time as switching tires. The -20mm offset would have been the old wheels with the 12.50 tires.

 

[Jay P]

No Problem.

For @Bubblehead with his 33x10.5 tires, I recommend that he run 1.0" spacers with his 15x8 5.5" backspace Ravine wheels to net 4.5" effective backspacing, available here: https://www.titanwheelaccessories.c..._wrangler~sz_wheel-spacers~yj_1-wheel-spacers He could also run 1.25" spacers to net 4.25" effective backspacing.

For @Jay P with his 33x12.5 tires, I recommend that he run 1.5" spacers with his 15x8 5.5" backspace Ravine wheels to net 4.0" effective backspacing, available here: https://www.titanwheelaccessories.c...rangler~sz_wheel-spacers~yj_1-5-wheel-spacers He could also run 1.75" spacers to net 3.75" effective backspacing.

Very helpful and those are great prices. I appreciate this!


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[Bubblehead]

What wheels are you wanting to use and what width, 7" or 8", are they? I need the width to be able to convert that useless -20mm offset measurement to the wheel's backspace dimension which is far more useful for Jeep and truck wheels.

Offset is a measurement that is only useful for car wheels, forget you ever heard it where Jeep wheels are concerned. Offset and backspace are not interchangeable terms, they measure two different dimensions.

Hi Jerry, thanks for the reply.
I understand the difference between “offset” and “backspacing”; I don’t agree or disagree with you regarding the uselessness of offset measurements, but, when looking on-line for wheels recently and asking sellers what the backspacing measurement was, most of the answers came back as an offset measurement, so they are both out there. I prefer backspacing - it’s what really matters!

Having said all of that and to answer your question; I have two sets of wheels;
- 15x8 Les Schwab ULTRA 62’s with a -20 mm offset (approx. 4” BS that I need to measure) - currently on the Jeep with 33x12.5 BFG Mud Terrain’s with NO interference issues.
- 15x8 OEM Ravine wheels with 5.5’ backspacing

My goals are:
1. Get the new tires that I haven’t bought yet (33x10.5x15 BFG ATs) under the OEM fender flairs (if I have to buy wider fender flairs (Bushwacker type) I’ll do that but would like to use the originals.
2. NOT hit or rub any suspension/steering/body parts.
3. To use either wheel noted above if it works as desired.

SO, there you go.
Thanks in advance for your advice.

 

[Bubblehead]

Very helpful and those are great prices. I appreciate this!


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For Jerry and Mr. Bills, I just posted a little more info (sorry its a little late), BUT, I agree with the solutions above. I have a set of 1.25” spacers that I test fitted the other day which basically gave me the same backspacing as the aftermarket -20 offset wheels. The only issue I need to address with the spacers is the previous owner upgraded the differential gear ratios and I think new rear axles (bought the JEEP from an ACURA dealer who just wanted to get rid of the Jeep - and the previous owner won’t talk to me - a whole other issue), so the rear axle wheel studs are about 3/4” shorter than the front axle studs, so the spacer lug nuts don’t get enough bit on the studs for my liking. Time to swap some studs!

 

[Bubblehead]

Maybe I'm reading into it, but it sounded to me like the OP was switching wheels at the same time as switching tires. The -20mm offset would have been the old wheels with the 12.50 tires.

Correct!

 

[Jerry Bransford]

The reason the wheel salesman you were working with could only speak of its offset dimension is because he is a car and car wheel guy, not a Jeep owner or someone familiar with how to sell Jeep and truck wheels. Anyone sufficiently expert with Jeep/truck wheels would only speak of the wheel's backspacing which is by far the more useful measurement.

For 10.5" tires, you only need to reduce the 5.5" of backspacing by around 1/2"... I.E. You only need to reduce that 5.5" backspacing down to around 5". That means you only need 1/2" of spacing to move the wheel out a half-inch. Anymore than that the tire will protrude further out than you said you want.

All of this is why I personally would not try to use factory wheels with larger than factory size tires... I refuse to buy wheels that don't have the correct amount of backspacing to begin with... to avoid the need to use wheel spacers.

Make sure too that you have the axles centered via adjustable length track bars. If they're not centered, you won't be able to tuck the tires in as much as you want to since they'll be too close on one side to use wheels with the most possible amount of backspacing as needed to keep them tucked in as far as possible.

 

[Mr. Bills]

To @Bubblehead:

If you want to use the factory Ravine 15x8 wheels with 5.5" backspacing, your 1.25" spacers will net 4.25" effective backspacing which is just fine for 10.5" wide tires. You would need to have a bad case of OCD to notice the difference between 4.25" and the 4.50-4.75" backspacing which is frequently recommended for 10.5" wide tires mounted on 8" wide wheels.

Your 1.25" spacers should also be okay for "metric 33's" which are typically about 11.2-12" wide, and may even work with some 33x12.5" flotation tires depending upon the brand and tread/sidewall sidebiters although the conventional wisdom is no more than 4" backspacing for 12.5" wide tires on 8" wide wheels.

If I were in your position I would try the spacers you have. If you hate the look you can always buy a set of 1" spacers, linked above.

Needing to change to longer wheel studs to use spacers is common. Sometimes it is necessary even without spacers, particularly with some aluminum wheels that have thick mounting pads. For example, I needed to change to longer JK studs for my rear Dana 44 when I changed over to chromoly axle shafts. The studs shipped with the axle shafts were too short for my aluminum wheels but would have worked fine with steelies.

I agree that choosing wheels with the correct backspacing to begin with is preferred to the use of spacers, but spacers and lug adapters are used by jeepers all the time with few verifiable reports of adverse results. I am currently in the market for new wheels myself and am seeking to avoid the use of spacers to correct backspacing - not due to safety concerns but because many tire shops won't touch wheels with spacers and I don't want to be 1,000 miles from home in a town where nobody will fix my tire because I am using spacers.

 

[bobthetj03]

Rubicon or Sahara flares are 1" wider and could aid in our tire tucking efforts. 4.25" BS and Rubi flares will achieve said tuckingness.

 

[Bubblehead]

To @Bubblehead:

If you want to use the factory Ravine 15x8 wheels with 5.5" backspacing, your 1.25" spacers will net 4.25" effective backspacing which is just fine for 10.5" wide tires. You would need to have a bad case of OCD to notice the difference between 4.25" and the 4.50-4.75" backspacing which is frequently recommended for 10.5" wide tires mounted on 8" wide wheels.

Your 1.25" spacers should also be okay for "metric 33's" which are typically about 11.2-12" wide, and may even work with some 33x12.5" flotation tires depending upon the brand and tread/sidewall sidebiters although the conventional wisdom is no more than 4" backspacing for 12.5" wide tires on 8" wide wheels.

If I were in your position I would try the spacers you have. If you hate the look you can always buy a set of 1" spacers, linked above.

Needing to change to longer wheel studs to use spacers is common. Sometimes it is necessary even without spacers, particularly with some aluminum wheels that have thick mounting pads. For example, I needed to change to longer JK studs for my rear Dana 44 when I changed over to chromoly axle shafts. The studs shipped with the axle shafts were too short for my aluminum wheels but would have worked fine with steelies.

I agree that choosing wheels with the correct backspacing to begin with is preferred to the use of spacers, but spacers and lug adapters are used by jeepers all the time with few verifiable reports of adverse results. I am currently in the market for new wheels myself and am seeking to avoid the use of spacers to correct backspacing - not due to safety concerns but because many tire shops won't touch wheels with spacers and I don't want to be 1,000 miles from home in a town where nobody will fix my tire because I am using spacers.

EXCELLENT! Thanks much Mr. Bills