Can I make the switch to a larger wheel without facing other issues?

[Unacceptable mouks]

The 8" width seems to be more available and less expensive. I've found two similar wheels in 8" width that have either a -27 or -19 offset and a 3.5 or 3.75 backspace. Are there any suggestions relative to the offset or backspace to ensure clearance? These seems pretty close in specs.

I spent some time looking at TJ pictures with various offsets before ordering my new wheels, 3.75" will stick out from the fender flares even if you have the Rubicon ones. Moab wheels have 5" of backspacing, you won't have any clearance issues with 3.75"

 

[BobK]

OK, so an 8" wide wheel, with 3.75" back spacing will clear the suspension, brakes, etc. and will have the tires stick out a bit from the flares, which is what I'm looking for. Not a huge stance outward, but it sounds like the difference would be minimal.

Thanks to all. When I get to this stage of my build, there will be plenty of pictures in my build thread. I just need to get tires and wheels ordered soon to be ready.

 

[crackedcornish]

33x10.50x15 KM2's on 15x8 M/T Classis II's with 3.6" of backspace..shown with 6" metalcloak flares

 

[BobK]

33x10.50x15 KM2's on 15x8 M/T Classis II's with 3.6" of backspace..shown with 6" metalcloak flares
View attachment 101021

That looks great. What made you choose 10.5 vs 12.5? Just curious since I haven't made up my mind yet.

 

[crackedcornish]

That looks great. What made you choose 10.5 vs 12.5? Just curious since I haven't made up my mind yet.

I originally bought them for a 4cyl YJ, so was looking for lighter weight and less rolling resistance, but then the YJ got these 31's that came on the TJ when I bought it instead

I haven't noticed any downside to the narrower tires in either my everyday driving or any of the wheeling I've done with them so far

 

[BobK]

The typical recommendation is to run 8" wide wheels with 12.50" wide tires. Reasons given usually include that the narrower width better protects against "popping" a bead at extremely low tire pressures. However, for the vast majority of jeepers this is a non-issue. I have run both wheel widths over the past 50+ years in many types of terrain and at very low tire pressures without any adverse incident. It is purely a matter of personal preference.

The bottom line is that one can run either 8" or 10" wide wheels with 12.50" wide tires so pick the width that you prefer, whether it be for reasons of aesthetics, availability, or whatever.

_____________

P.S. - Forget offset. Without getting into the reasons why, it is not a particularly useful measurement for jeepers.

The measurement you need to focus on is backspacing - the distance between the wheel mounting surface and the inside edge of the wheel. Optimum is 4" backspacing with an 8" wide wheel, although some like the tires "pushed out" more with 3.75" backspacing. Generally speaking, backspacing of 3.75" - 4.25" should work with your desired 33x12.50R15 tires, perhaps as much as 4.5".

You comment about running 12.5" tires on a 8" wide rim has sparked a thought. I kind of like the wheels I have but they are 7.5" wide. Could I run a 33 x 10.5 x 15 on this same rim and avoid purchasing new wheels?

 

[bobthetj03]

You comment about running 12.5" tires on a 8" wide rim has sparked a thought. I kind of like the wheels I have but they are 7.5" wide. Could I run a 33 x 10.5 x 15 on this same rim and avoid purchasing new wheels?

What BS do your current wheels have?

 

[Mr. Bills]

You comment about running 12.5" tires on a 8" wide rim has sparked a thought. I kind of like the wheels I have but they are 7.5" wide. Could I run a 33 x 10.5 x 15 on this same rim and avoid purchasing new wheels?

Absolutely. That size tire calls for 7-9" rim width. Unless the backspacing of your existing wheels is more than 5" you should not have a problem.

See: https://tiresize.com/tiresizes/33X10.50R15.htm

 

[BobK]

What BS do your current wheels have?

Sadly, I have no idea. They were on the Jeep when I bought it. I'm not certain that they are original but they are in fair to good condition. At the rate I'm spending money, it would be great if I could get them cleaned up and re-used. If that means 10.5 vs 12.5 tires I think I can live with that.

 

[BobK]

If I wanted to get my own measurement of the current wheels, I know I'd have to take it off the Jeep, but would I also need to get the tire removed?

 

[bobthetj03]

Sadly, I have no idea. They were on the Jeep when I bought it. I'm not certain that they are original but they are in fair to good condition. At the rate I'm spending money, it would be great if I could get them cleaned up and re-used. If that means 10.5 vs 12.5 tires I think I can live with that.

Pull a wheel and measure BS. Anything over 5" of BS and your front tires will rub the lower control arms and front sway bar at full lock, even with a 10.50" wide tire.

Just find a straight edge long enough to reach the wheel lips at each end.

 

[Mr. Bills]

This calculator will help you visualize the differences in fitment with different wheels and tires: https://www.rimsntires.com/specspro.jsp

As far as measuring backspace, you do not need to remove the tire from the wheel. Just measure as described by @bobthetj03 .

 

[BobK]

I will pull a wheel this evening and try to get measurement of what I have. More to come!

Thanks

 

[BobK]

I must be getting old and forgetful. There is another reason why I was going to buy new wheels. I only have four wheels, the spare is an old steel wheel (likely factory) and I'm installing a rear bumper with tire carrier, so I need a fifth wheel that matches.

 

[crackedcornish]

I must be getting old and forgetful. There is another reason why I was going to buy new wheels. I only have four wheels, the spare is an old steel wheel (likely factory) and I'm installing a rear bumper with tire carrier, so I need a fifth wheel that matches.

well, I was going to suggest you just measure your spare's backspace instead of removing a wheel...

 

[astjp2]

your tires can run the frame with too much backspace.

I must be getting old and forgetful. There is another reason why I was going to buy new wheels. I only have four wheels, the spare is an old steel wheel (likely factory) and I'm installing a rear bumper with tire carrier, so I need a fifth wheel that matches.

You dont have to have a matching spare, you just want one...admit it ~

 

[papageorgio2121]

I am running 33" x 12.5" x 15" on 15" x 8" American Racing rims and couldn't be happier!

View attachment 100988

what kind of lift do you have on it? looks great btw!

 

[Mikester86]

what kind of lift do you have on it? looks great btw!

From what the forum members have been able to help me figure out, as I bought it with the 4” lift. Currie control arms, springs are possibly Currie or Rubicon Express. In the small time I looked, I haven’t found an identifier on them. Track bar may also be Rubicon Express. Shocks are Rancho 5000’s, I am saving for new Rancho 5000X’s.

Thank you for the compliment, like most, I have already invested a lot of time and money into it. As it needed some TLC from PO’s neglect. I named her WIP, as in work in progress. Although Money Pit would have worked as well!

 

[BobK]

Bit the bullet and just order some Mickey Thompson chrome wheels. 15 x 8 with 3.625 backspacing and -22 offset

Finger crossed it all works out.

 

[MountaineerTom]

I must be getting old and forgetful. There is another reason why I was going to buy new wheels. I only have four wheels, the spare is an old steel wheel (likely factory) and I'm installing a rear bumper with tire carrier, so I need a fifth wheel that matches.

You could put a spare tire cover on the spare temporarily until you decide what you want, or save up or whatever. I just bought a mastercraft spare cover for the spare on my utility trailer for about $30.