Trying to decide between 33" and 35" BFG K03s

[mojowrangler]

My build: '97 Jeep Wrangler Sport, automatic/32RH, 4.1 geared Dana44 front and rear with lockers, 3.5" suspension lift + 1" body lift. I have the original/stock transfer case (not modified or upgraded to the lower geared Rubicon transfer case). I currently have 35" KM3 tires (35X12.50R17) on 17" aftermarket Walker Evans Racing (WER) wheels.

These KM3 tires are in good condition, but don't do well on ice and hard-packed snow, which is a lot of what I will be driving on to get to the trails in Colorado this winter. This vehicle is primarily for trail riding, not an everyday vehicle, but I still want to be safer on the roads in the winter in Colorado.

I bought an extra set of 16" Moab wheels (which were OEM Jeep Wrangler TJ Rubicon wheels) that I plan to put some A/T-3PMSF tires on. I'm leaning toward buying BFG KO3 tires (maybe Falken Wildpeak AT4W, but I like the weight of the KO3s, plus what I've seen in comparison reviews). Now I'm deciding what size tires I should get. I suspect that I will get better overall performance for my build with 33" tires versus 35" tires based on the research I've done so far, and an opportunity I had to drive this Jeep recently with a "temporary" set of 30" tires for testing (see first half of pic below). The power increase with the 30" tires is most noticeable climbing long steep paved roads. Logically, the 33" tires should perform somewhere in between the 30" tires I tested and the 35" tires that I have on it now (see lower half of picture below).

I suspect some folks might tell me it's a matter of preference or the difference will not be that noticeable. That is fine. I'm trying to micro-optimize here! From my perspective there are two advantages to keeping the 35" tires - it arguably looks better and I'll have a small amount of additional clearance. On the other hand, the advantages to the 33" tires should be a small decrease in weight, improved acceleration/stopping, less stress on the drivetrain, and improved gas mileage. I have no idea if these will be noticeable differences that I should care about. I also don't "think" it will look that bad with 33s, versus 35s.

Here's what it looks like with 33s and 35s...

So, the 33s will be somewhere in between. If/when I get the 33" K03s on 16" wheels, I will switch back to the 35" KM3 on 17" wheels when the weather is warm again. I'll probably switch back and forth between the warm/KM3 and colder/KO2 weather tires until the KM3s are worn down or too old to use.

I think this makes the most sense for my situation, but I thought I would post something here in case there's something I'm not thinking about in stepping down from 35" tires to 33" tires on this vehicle. FWIW, the exact size of the 33s I'm looking at are 285/75R16 (32.8"). There's also a 295/75R16 (33.4").

Also, FWIW, I don't have any body clearance issues (no rubbing) with the 35" tires that are on it now and it runs "fine" - it just ran "better" with the 30" tires as expected (for road use). I just suspect that 33" is more "appropriate" for this vehicle than 35" for my use...trail riding with some difficult trails, but I'm not looking for extreme obstacles. It has great clearance with the 35s, and I suspect I won't notice much loss with the 33s, but I'm curious what other think based on my particular build.

 

[Tob]

Those Moab wheels likely have more backspacing than your Walker Evans wheels, which means you will have less clearance in some areas even with smaller tires. The answer would be wheel spacers or different wheels. That’s the only thing I see that you may have missed. Braking and acceleration do stand to gain noticeably with smaller tires. An alternate set of road tires is sensible and something that I’ve considered doing as well.

 

[mojowrangler]

Those Moab wheels likely have more backspacing than your Walker Evans wheels, which means you will have less clearance in some areas even with smaller tires. The answer would be wheel spacers or different wheels. That’s the only thing I see that you may have missed. Braking and acceleration do stand to gain noticeably with smaller tires. An alternate set of road tires is sensible and something that I’ve considered doing as well.

I should have mentioned the spacers... I am running a 1.25" spacer right now. But I will check the difference in backspacing between the two wheel sets. Good point.

 

[srimes]

I went from old 35 MTs to fairly fresh 33ATs, mainly looking for better road manners. https://wranglertjforum.com/threads/considering-going-smaller-7-35s-to-5-33s.77680/page-2

So far I've been very pleased with the 33s, on road and off. But this is my first winter with them and and what stops me is a lack of floatation, so I know they won't do as well when pushing limits. My plan is to get some WIDE 35s for winter trail use, and run the 33s the rest of the time.

There's no doubt that bigger tires look better, and in traction-limited situations they'll usually work better, too. The clearance difference is small and I bet you'd be happy with the 33s in the summer. But you say this is primarily for trail rides and you're in a place with lots of snow, so I'd go for the 35s. That extra sidewall will let you air down more which does make a big difference.

 

[mojowrangler]

OK, bear with me on some math to figure out (theoretically) what is gained/lost in this tire change (distance from tire to body of Jeep)...

My 17" WER wheels have a ~4" backspacing. I did my best to measure this while the wheels are mounted, so I could be a little off, but probably not by much. The WER wheels are 8.5" (per the wheel stamp). So, their offset is 4 - (8.5 / 2) = -0.25 (the WER wheels are centered 1/4" away from the Jeep). My 16" Moab wheels are 8" wide with a 5" backspace. That means their offset is 5 - (8 / 2) = 1 (the Moab wheels are centered 1" toward the Jeep). So, the Moab wheels will put my tires (from center line) approximately 0.75" closer to the Jeep than my current tires.

But the tires that I am considering are a little narrower...

Per standard sizing the 35X12.5R17 tires on the WER wheels are 12.5" wide, and the 285/75R16 tires that I am considering on the Moab wheels are 285 / 25.4 ~= 11.2". Without considering the wheels, the sides of the 33" KO2s that I am considering should be (12.5 - 11.2) / 2 = 0.65" farther away from the vehicle than the KM3s currently on the vehicle. Considering the wheel offset difference and tire width difference, the new tires should be approximately 0.75 - 0.65 = 0.1" closer to the vehicle than the current tires.

So that seems like a wash, unless I screwed something up in my math (wouldn't be the first time). But it seems pretty intuitive, both from the math and just thinking about the differences in wheels and tires. Also, keep in mind that the diameter of the tires is less, decreasing chances of rubbing during steering.

 

[mojowrangler]

I went from old 35 MTs to fairly fresh 33ATs, mainly looking for better road manners. https://wranglertjforum.com/threads/considering-going-smaller-7-35s-to-5-33s.77680/page-2

So far I've been very pleased with the 33s, on road and off. But this is my first winter with them and and what stops me is a lack of floatation, so I know they won't do as well when pushing limits. My plan is to get some WIDE 35s for winter trail use, and run the 33s the rest of the time.

There's no doubt that bigger tires look better, and in traction-limited situations they'll usually work better, too. The clearance difference is small and I bet you'd be happy with the 33s in the summer. But you say this is primarily for trail rides and you're in a place with lots of snow, so I'd go for the 35s. That extra sidewall will let you air down more which does make a big difference.

I think what I need to be careful of, as @Tob pointed out, I might run into an issue with rubbing if I put 35" tires on those Moabs instead of 33" tires. I can probably max out my steering and see how much room I have to play with. I'm not ruling out 35" tires (A/T-3PMSF is the primary requirement). I suppose I "want" the 35" for the looks, but it would be nice to get a little power back on the road too.

Do you notice a difference between your 33s and 35s pushing your Jeep up long, steep, paved roads? This is where I noticed the difference in the 30s versus 35s, but if its not much of a difference between 33s and 35s, I might stick with 35s. I need to borrow someone's 33" wheel/tires and go for a test drive! I'll bet guys in tire shops use discard tires off customer vehicles for this kind of testing.

 

[srimes]

I think what I need to be careful of, as @Tob pointed out, I might run into an issue with rubbing if I put 35" tires on those Moabs instead of 33" tires. I can probably max out my steering and see how much room I have to play with. I'm not ruling out 35" tires (A/T-3PMSF is the primary requirement). I suppose I "want" the 35" for the looks, but it would be nice to get a little power back on the road too.

Do you notice a difference between your 33s and 35s pushing your Jeep up long, steep, paved roads? This is where I noticed the difference in the 30s versus 35s, but if its not much of a difference between 33s and 35s, I might stick with 35s. I need to borrow someone's 33" wheel/tires and go for a test drive! I'll bet guys in tire shops use discard tires off customer vehicles for this kind of testing.

My jeep definitely felt quicker with the 33s. I noticed it more when accelerating from a stop. They felt a lot lighter when I was putting them on the lugs, too.

 

[mojowrangler]

My jeep definitely felt quicker with the 33s. I noticed it more when accelerating from a stop. They felt a lot lighter when I was putting them on the lugs, too.

I was feeling pretty old when I changed the tires/wheels and I tried lifting those 35s for the first time.. I felt better when I found out my tires/wheels are 110 pounds each. Getting the spare on/off the back was a fun challenge too. I definitely don't want to ever deal with heavier tires/wheels - not by myself anyway.

 

[AndyG]

I have both-

35’s look so good

33’s work with less work.

 

[James9100]

35s take a lot more moola to properly build for, plenty of good threads on this subject.
A comparison of building for 33s and 35s
Love the look of 35s too but for what I use my Jeep for I just can’t justify the cost so I’m sticking with 33s.

 

[AndyG]

33’s above- 2” lift plus 1.25” body lift if I remember correctly

35” on 4 inch plus an inch and a half of body lift

 

[mojowrangler]

I just did a ton of reading on this subject - more than I should probably admit. Long story short, given what I use the Jeep for and its 4.1 gearing with the 32RH, I'm probably better off with the 33" over the 35". It's kind of amazing how much people have anguished in their lives over seemingly little differences in tire sizes and gear ratios. And now I've been sucked into this evil black hole myself.

 

[JMT]

I just did a ton of reading on this subject - more than I should probably admit. Long story short, given what I use the Jeep for and its 4.1 gearing with the 32RH, I'm probably better off with the 33" over the 35". It's kind of amazing how much people have anguished in their lives over seemingly little differences in tire sizes and gear ratios. And now I've been sucked into this evil black hole myself.

35’s. Easy choice

 

[jjvw]

35s work better than 33s do.

 

[TheBoogieman]

35s take a lot more moola to properly build for, plenty of good threads on this subject.
A comparison of building for 33s and 35s
Love the look of 35s too but for what I use my Jeep for I just can’t justify the cost so I’m sticking with 33s.

If you build it properly for 33s, then it's good for 35s. Gearing is the exception IMO.

 

[mojowrangler]

I ended up buying some 285/75R16 KO3s today. They are definitely set in a little more than my other wheel/tire set (narrower stance due to wheel/tire geometry). The difference in looks is about what I was expecting - a little more conservative and proportioned, and a little less aggressive and cartoonish. But the difference is subtle and I probably notice more since I've spent so much time considering wheel and tire configurations lately. Now, I'll be happy to not think about this for a while! I also tested steering clearance - no issues, and dropped from 38 PSI (set by Discount Tire) to 32 PSI based on my initial chalk test. I'll do the chalk test again soon to double-check. I suspect I could/should drop even lower, but 32 PSI looks close enough for now. I'll try to get it out on the trails this weekend.

Here it is with new 285/75R16 (~32.8") KO3s on the 16" Moab wheels...

 

[AdventurePig]

My build: '97 Jeep Wrangler Sport, automatic/32RH, 4.1 geared Dana44 front and rear with lockers, 3.5" suspension lift + 1" body lift. I have the original/stock transfer case (not modified or upgraded to the lower geared Rubicon transfer case). I currently have 35" KM3 tires (35X12.50R17) on 17" aftermarket Walker Evans Racing (WER) wheels.

These KM3 tires are in good condition, but don't do well on ice and hard-packed snow, which is a lot of what I will be driving on to get to the trails in Colorado this winter. This vehicle is primarily for trail riding, not an everyday vehicle, but I still want to be safer on the roads in the winter in Colorado.

I bought an extra set of 16" Moab wheels (which were OEM Jeep Wrangler TJ Rubicon wheels) that I plan to put some A/T-3PMSF tires on. I'm leaning toward buying BFG KO3 tires (maybe Falken Wildpeak AT4W, but I like the weight of the KO3s, plus what I've seen in comparison reviews). Now I'm deciding what size tires I should get. I suspect that I will get better overall performance for my build with 33" tires versus 35" tires based on the research I've done so far, and an opportunity I had to drive this Jeep recently with a "temporary" set of 30" tires for testing (see first half of pic below). The power increase with the 30" tires is most noticeable climbing long steep paved roads. Logically, the 33" tires should perform somewhere in between the 30" tires I tested and the 35" tires that I have on it now (see lower half of picture below).

I suspect some folks might tell me it's a matter of preference or the difference will not be that noticeable. That is fine. I'm trying to micro-optimize here! From my perspective there are two advantages to keeping the 35" tires - it arguably looks better and I'll have a small amount of additional clearance. On the other hand, the advantages to the 33" tires should be a small decrease in weight, improved acceleration/stopping, less stress on the drivetrain, and improved gas mileage. I have no idea if these will be noticeable differences that I should care about. I also don't "think" it will look that bad with 33s, versus 35s.

Here's what it looks like with 33s and 35s...

View attachment 573603

So, the 33s will be somewhere in between. If/when I get the 33" K03s on 16" wheels, I will switch back to the 35" KM3 on 17" wheels when the weather is warm again. I'll probably switch back and forth between the warm/KM3 and colder/KO2 weather tires until the KM3s are worn down or too old to use.

I think this makes the most sense for my situation, but I thought I would post something here in case there's something I'm not thinking about in stepping down from 35" tires to 33" tires on this vehicle. FWIW, the exact size of the 33s I'm looking at are 285/75R16 (32.8"). There's also a 295/75R16 (33.4").

Also, FWIW, I don't have any body clearance issues (no rubbing) with the 35" tires that are on it now and it runs "fine" - it just ran "better" with the 30" tires as expected (for road use). I just suspect that 33" is more "appropriate" for this vehicle than 35" for my use...trail riding with some difficult trails, but I'm not looking for extreme obstacles. It has great clearance with the 35s, and I suspect I won't notice much loss with the 33s, but I'm curious what other think based on my particular build.

I’ve been considering this same thing. Going from 315/75r16’s to 295/75’s or 285/75’s

My thought is that cost, weight, performance, durability, etc, would all probably improve, especially with a less aggressive A/T tire compared to our M/T Patagonia’s

 

[AdventurePig]

I ended up buying some 285/75R16 KO3s today. They are definitely set in a little more than my other wheel/tire set (narrower stance due to wheel/tire geometry). The difference in looks is about what I was expecting - a little more conservative and proportioned, and a little less aggressive and cartoonish. But the difference is subtle and I probably notice more since I've spent so much time considering wheel and tire configurations lately. Now, I'll be happy to not think about this for a while! I also tested steering clearance - no issues, and dropped from 38 PSI (set by Discount Tire) to 32 PSI based on my initial chalk test. I'll do the chalk test again soon to double-chalk. I suspect I could/should drop even lower, but 32 PSI looks close enough for now. I'll try to get it out on the trails this weekend.

Here it is with new 285/75R16 (~32.8") KO3s on the 16" Moab wheels...
View attachment 574151

View attachment 574152

Nice. I think that looks just fine! Have fun testing them out!

 

[mojowrangler]

I also weighed this wheel/tire combo (285/75R16 KO3s on 16" Moabs) at 88.2 pounds, versus 110 pound for my alternate wheel/tire combo (35X12.50 on 17" WERs). I didn't change the spare on this KO3/Moab set yet. I'm being cheap and waiting to get a used 285/75R16 spare tire for my 5th Moab wheel, figuring the 35" spare (from my WER wheel set) could be used "carefully" if I need a spare sooner than later in an emergency. However assuming all 5 get swapped and are close in weight, the difference per tire is approximately 110 - 88.2 = 21.8 pounds, or 21.8 * 5 = 109 pounds in overall reduced weight of the vehicle. 109 pounds isn't a huge difference, but my understanding is that the additional 21.8 pounds in rotational mass per tire could be noticeable - time will tell!

 

[James9100]

Looks good!
26psi is the common recommendation for that tire size.