What is the biggest size tire I can fit with no lift on a Jeep Wrangler JK?

Chris

Administrator
Staff Member
Joined
Sep 28, 2015
Messages
32,389
Location
Florence, AZ
One of the most frequently asked questions on this forum is “What's the largest tire I can fit on my stock / unlifted 2007+ Jeep Wrangler JK?”. So, I put this post together so that we can link to whenever this question arises.


Preface
I'd like to preface this by answering the question in simple terms first. Assuming you have the right wheels, you can fit a 35" tire without a lift on a Jeep Wrangler JK. However, it will be very, very tight, and highly unadvisable. Fitting a 33" without a lift is more realistic, but still leaves a lot to be desired. You shouldn't be asking "What is the largest tire I can fit on a Jeep Wrangler JK without a lift?", what you should be asking is, "What is the largest tire I should run on my Jeep Wrangler JK without a lift?". The answer to that is very simple: You should not be running any tire larger than the factory size without lifting your JK accordingly.

The reason for this is that when you increase tire size without adding lift, you effectively reduce the amount of up-travel from your suspension, therefore dramatically decreasing the ride quality of your Jeep. If you think this will only be apparently obvious when off-roading, you are sorely mistaken. Reduced up-travel will be felt both on-road and off-road. Want to throw those 33" or 35" tires on your stock height JK just because you know they'll fit? Well, I hope you're ready for a terrible ride, because that's what you're going to get.

Again, you should not run any tire larger than stock without lifting the vehicle accordingly. 33s generally pair well with a 2" lift, and 35s are best paired with a 3.5" lift.


Now let's get into the details
First things first, Jeeps come stock with three different tire sizes:
  1. 225/75/16 (29”x9”)
  2. 255/75/17 (32”x10”)
  3. 255/70/18 (32”x10”).
The backspacing on stock JK wheels is 6.25". That means that the mounting surface of the wheel is 6.25” from the rear lip of the wheel. The larger the backspace number, the further under the fender (and closer to suspension components and airdam) the wheel will be (see below image).

40-RWD-Wheel-diagram.jpg


I see posts all the time saying that a 33” tire will fit the stock JK just fine, and that is semi-true. In reality, this question requires a 2 part answer. The first part deals with tire diameter. The second part deals with width.

It is true that the largest diameter tire you can fit on a stock JK without issue (read on) is 33” in diameter. With this diameter, you shouldn’t have any issues on the street. However, you could get some contact with your fenders if you flex offroad. Disconnecting your front sway bar will cause contact with your fenders.

Now let’s take a look at tire width. People often overlook this aspect when choosing a tire. The width on most 33's range from 10” – 12.5”+.


On Stock Wheels
The largest tire you can fit without a chance of problems on road is a 33x10 tire (also called a “pizza cutter”). An example is the 255/80/17 BFG KM2. Because this tire is the same width as most stock JK tires, there is no issue on road, despite the larger diameter. You can run this size without issue.

Now, let’s consider some tires that could potentially cause slight issues on road; the 33x11s. The common sizes of these would be 285/75/16, 285/70/17, and 275/70/18.

The 275/70/18 measures slightly under 11” wide, while the other two measure a little over. Many folks have reported running these sizes without issue. However, others have experienced contact with the airdam or front suspension components. Simple fixes are to add washers to the steering stops, trim the airdam, or install wheel spacers.

Any tire larger than 11” in width, you are almost guaranteed to have to do one of the above mentioned mods. In fact, if you go too much wider than the 11” tire on stock wheels, you stand a good chance of making contact with your rear swaybar end link. If that is the case, wheel spacers can correct this issue. Common sizes are 295/70/17 (33x11.6), 305/60/17 (33x12), 305/70/16 (33x12), 295/65/18 (33x11.6).


On Aftermarket Wheels
As I mentioned initially, the stock wheels have a backspacing of 6.25”. This is too deep of a backspace to allow proper clearance for a decently wide tire. The general consensus is that the “magic number” for backspacing for the JK is 4.5” or less. It does not mean you can't run a wheel with 4.6”+. But 4.5” and under is the safest bet.

Many 15” wheels have less (sometimes a lot less) than 4.5”. That's so the wheel clears the brake calipers. Most 15” wheels come with 3.75” of backspacing (MB72, MB TKO, etc). There are a few that come with more (such as the Black Rock 909 – 4”) and some that come with less (such as the Level 8 Tracker – 3.32”). Just remember, the lower the backspace number, the further out the wheel will sit from the Jeep body. One of the most common wheel/tire combos on this site is the 15x8 MB 72 wheel with 33x12.5x15 Duratrac tires. Dozens of people run this setup without a single issue on the street. However, just like most of the other 33” combinations, you can get some fender contact when offroad.

Also, be aware that, while many 15" alloy wheels will fit over the Wrangler's brake calipers, most 15" steel wheels will not.

Once you get into 16”+ wheels, it's pretty easy to select a wheel with a backspace near 4.5”. The most common 33” tire to run with 16” aftermarket wheel is the 285/75/16. A common tire size for the 17” wheel is the 285/70/17.

Links of interest:
Utility to compare tire sizes
Wheel / tire fitment calculator
 
Thank you! Very helpful information. What is the largest tire that will mount on the OEM mount and bumper on a 2007 with OEM wheels?
 
  • Like
Reactions: Danarch
Hi all, I’m trying to figure out why tires to get for my daughter’s 2017 wrangler sport. It won’t be off-roading much and just want a size that will ride well, not bog it down, not kill the mileage and most of all LOOKS GOOD.

Stock are 255/75/17 and am thinking of getting 275/65/18 in a BFG KO Type tire with some black rims.

Is this about the biggest size I can get without having any rubbing issues? What offset should I be looking for in the rims? Thanks
 
Do you know what gears are in it, if they are 3.21's you might need to do a gear change. The 65 will be a wider tire then a 70 or 75.

I just checked and you won't need to do a gear change but your not gaining anything but a little wider tire.

 
Last edited:
Do you know what gears are in it, if they are 3.21's you might need to do a gear change. The 65 will be a wider tire then a 70 or 75.

I just checked and you won't need to do a gear change but your not gaining anything but a little wider tire.

Not sure about the gears, it’s a stock sport so whatever it came with. Yeah that size tire is about the same diameter as the stock tires, what I’m looking for is an AT tire with a bolder look, nicer rims etc.
 
09 Rubicon 6 speed manual, as far as I can tell stock height so here is the real question.
Are there really any advantages of putting bigger tires on? I do a little light off roading mostly mud, I love mud.

Everyone keeps asking me when I am going to put 35's on. I don't think I would go 35 maybe a 33. But if I were to go 33's i have a few questions.

I don''t really care about the gap between the body and bumpers as I have put steel on the front and rear and there is a gap anyway.

I have the Rubi Rails on it and behind those the pinch seam is at the same distance as the rails, which looks to be about 1.5 in away from the tire 255/27R17. The Rubi Rails are coming off because 1. they are rusting and 2. I will be putting side step on it, so I would still be concerned with the pinch seam rubbing. See image. I do not have stock rims and I don't know their size other than being 17's.

I took it to Discount tire, they said the rims will work but I need a 3" lift to keep a 33" from rubbing. Would that be a true statement? When I bought the Jeep there was a unopened boxed 2" body lift kit, Would that be advisable?
I have done a lot of searching on lifting the body and have found 1 major problem with a body lift. I cannot find a lift kit for the motor and transmission. All I can find on that is a 1" lift for the motor only. Any help with that would be welcomed.
I don't believe I have left out any vehicle info but if I have let me know.
Thanks for any help!

IMG_0226.jpg
 
Your rims will not work for 33s.. Read this thread you just posted in, specifically the post RIGHT ABOVE yours.
 
IMG_0227[107].jpg

Thanks for the reply and I'm guessing you are replying to the part about Discount tires, but as I stated my rims are not stock.
In the first post this thread Chris wrote,
On Stock Wheels
The largest tire you can fit without a chance of problems on road is a 33x10 tire (also called a “pizza cutter”). An example is the 255/80/17 BFG KM2. Because this tire is the same width as most stock JK tires, there is no issue on road, despite the larger diameter. You can run this size without issue.
 
@Chris, thanks for the awesome job compiling the sizing information. Very well done.

One thing I do not see mentioned much, and I ran into today, is wheel width. The stock 17” wheel on my 2015 JKU Rubicon is a 7.5” wide rim. That coupled with the negative offset of the stock rim was not conducive to my planned build. So I bought some Mammoth wheels that were 17x9.5 with a 4.5 offset. Pretty much what I would call a neutral wheel. Meaning the mount point is closer to the center of the wheel. I planned on running the 255/75R17 for a while before getting new bigger tires. Well, come to find out the shop would not fit a 255 tire on my new rim. It was actually too wide for the tire. They shot me a pretty good deal on some BFG AT AXO’s in 285/70R17 which fit my build, even though I really wanted a taller tire.

Anyhow, the point here is that you also need to consider wheel width. It seems that most aftermarket wheels come in 17x9, the ones I really wanted just happed to be a bit wider. Nothing I had considered until today. The extra half inch will mean that the tire is probably a fraction less tall than it would be on a 7.5” rim. Just food for thought.

IMG_1632.jpeg
 
  • Like
Reactions: Chris and tJKrider
@Chris, thanks for the awesome job compiling the sizing information. Very well done.

One thing I do not see mentioned much, and I ran into today, is wheel width. The stock 17” wheel on my 2015 JKU Rubicon is a 7.5” wide rim. That coupled with the negative offset of the stock rim was not conducive to my planned build. So I bought some Mammoth wheels that were 17x9.5 with a 4.5 offset. Pretty much what I would call a neutral wheel. Meaning the mount point is closer to the center of the wheel. I planned on running the 255/75R17 for a while before getting new bigger tires. Well, come to find out the shop would not fit a 255 tire on my new rim. It was actually too wide for the tire. They shot me a pretty good deal on some BFG AT AXO’s in 285/70R17 which fit my build, even though I really wanted a taller tire.

Anyhow, the point here is that you also need to consider wheel width. It seems that most aftermarket wheels come in 17x9, the ones I really wanted just happed to be a bit wider. Nothing I had considered until today. The extra half inch will mean that the tire is probably a fraction less tall than it would be on a 7.5” rim. Just food for thought.

View attachment 127383

Good advice!

Also, that's a fine looking Rubicon!
 
  • Like
Reactions: Ratbikerod