Question about wheel/tire sizes?

[jlg]

Folks, I'm thinking of the Sport-S with Max towing. I will be doing some towing (nothing more than 2-4klbs for the most part), mostly on-road, but some offroad also (nothing radical/rockclimbing/etc.).

I was thinking of the following:
KMC XD Rockstar III
BFG All-Terrain T/A KO2 tires (LT245/75R17)

A few questions:
I was thinking of just replacing with 17" like the stock, but Is there any advantage/disadvantages of doing 18" or 20" wheels? (better gas, worse offroad, etc.?)
WILL an 18 or 20" FIT on a stock Sport-S?
How is the road noise for the BFG K02's?

There are a number of different tire sizes for each of the wheel sizes, but not sure exactly how to read them.
LT245/75R17 -- I understand this one
LT315/70R17 -- would a wider tire like this fit (or a 305??) stock? Any advantage/disadvantage on the Gladiator to go wider?
LT35X12.5R17 -- does THIS mean a 35" tire (not really sure how to read this nomenclature) Will this fit stock?
LT37X12.5R17 -- is this a 37"? Prob will NOT fit the stock without modification, yes (and not sure I need them to be honest).

Any reviews from folks who have the wheels/tires?

Thanks -- sorry for the newbie questions -- never had a Jeep before....

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[jurfie]

Folks, I'm thinking of the Sport-S with Max towing. I will be doing some towing (nothing more than 2-4klbs for the most part), mostly on-road, but some offroad also (nothing radical/rockclimbing/etc.).

I was thinking of the following:
KMC XD Rockstar III
BFG All-Terrain T/A KO2 tires (LT245/75R17)

A few questions:
I was thinking of just replacing with 17" like the stock, but Is there any advantage/disadvantages of doing 18" or 20" wheels? (better gas, worse offroad, etc.?)
WILL an 18 or 20" FIT on a stock Sport-S?
How is the road noise for the BFG K02's?

There are a number of different tire sizes for each of the wheel sizes, but not sure exactly how to read them.
LT245/75R17 -- I understand this one
LT315/70R17 -- would a wider tire like this fit (or a 305??) stock? Any advantage/disadvantage on the Gladiator to go wider?
LT35X12.5R17 -- does THIS mean a 35" tire (not really sure how to read this nomenclature) Will this fit stock?
LT37X12.5R17 -- is this a 37"? Prob will NOT fit the stock without modification, yes (and not sure I need them to be honest).

Any reviews from folks who have the wheels/tires?

Thanks -- sorry for the newbie questions -- never had a Jeep before....

There is no advantage to changing your wheel size - it is only done for aesthetic-purposes and sometimes to increase the number of tire sizes available (17" is pretty well covered, however). Bigger wheels with the same tire diameter will mean less sidewall, which is not ideal for offroad purposes. Wheel size will not affect mpgs, but tire diameter and width will.

18s and 20s will fit a Sport-S.

BFG KO2s are a pretty mild tread compared to mud terrain tires; KO2s are a hybrid made for both on and offroad, so they are quieter than more aggressive treads, but not as quiet as a street tire.

Wider tires are better offroad as they have more contact with the terrain, especially aired-down. Narrower tires can still be good, especially if you don't do serious rock-crawling. Overlanders seem to prefer narrower tires, and they also have an mpg advantage over wider tires of the same diameter so more range/tank.

LT35x12.5R17 = 35" tall x 12.5" wide on a 17" wheel. Those sizes are nominal, however and will vary based on the wheel width, vehicle weight and air pressure. They will fit a Sport-S with no lift. 37s will fit, but will rub offroad when articulating at full wheel-turn. They fit on unlifted Rubicons due to the hiline fenders, but you can fit them on a Sport-S with a small lift to avoid rubbing. You probably don't need 37s, but many people (myself included) prefer the look.

 

[jlg]

Thanks for this -- what about a 285/75 R17? Would that width fit ok -- seems like it would be a bit better for offroad, but not TOO wide for on-road. I just want to make sure it wouldn't rub at extreme lock or during off-road.

 

[jurfie]

That size is 11.3" wide on an 8" wide rim. Rubbing will depend on the wheel offset. I just looked at the KMC XD Rockstar III you are considering to see what the offset is, but their website says it does not fit a JT.

 

[jlg]

Strange, tirerack says it does! I may just stick with the stock tires and have them put on the new rims until I decide what I want for tires....

 

[Backwoodsraider]

I am running 275/70/18 (33" tire) on 18x9 wheels. The wheel backspace is 4.5". Means the wheel sticks out about 4 inches farther then stock. Stock sport S. on turning the wheel, the tires hit the plastic on the damn between the front bumper and the fender.
Sport S with max tow

Using a lower backspace wheel, you should be able to run 33" without trimming. Maybe 34's.

Disadvantage to 18's - tires are less readily available at a decent price. Stick with 17's. (went with 18's to use on my grand cherokee, but sold it and kept the wheels. really good deal on them)

 

[danielspivey]

I run the 285/75r17 falkens and love them. 17” Jeep rubicon Rims. No lift.

 

[jlg]

Thanks for the pic -- looks great! Do these rub at ALL? (lock-to-lock turns? offroad?)

 

[danielspivey]

Thanks, these tires actually handle better and are quieter than the stock tires, and handle better than Michelin’s that came w rubi rims when I bought them. Quiet wise same as michelins.

no rubbing and didn’t have to remove that piece between the bumper and fender.

I run 35 psi and the steering stability is like night and day vs. stock tires and high psi

Note: if you go wider than 285 most tire manufactures will not recommend putting on a stock rim, therefore most shops won’t install. Also I imagine if you went bigger than manufacture suggested and you had an accident or blow out you’d be screwed...

 

[Mark Doiron]

...
There are a number of different tire sizes for each of the wheel sizes, but not sure exactly how to read them.
LT245/75R17 -- I understand this one
LT315/70R17 -- would a wider tire like this fit (or a 305??) stock? Any advantage/disadvantage on the Gladiator to go wider?
LT35X12.5R17 -- does THIS mean a 35" tire (not really sure how to read this nomenclature) Will this fit stock?
...

I've been running the 315s on my JK for the past couple years. Wonderful tire. Replaced Goodyear Duratracs. While I never had an issue with the Duratracs, a friend of mine with whom I do a lot of overlanding did. Flats. Way too many. We both carried two spares on most of our adventures because we were often a long ways from support (such as in the Arctic), and flats are really a problem in those situations. I ran 35 E-rated and he ran 33 D-rated. I opted for the KO IIs because they have stronger sidewalls.

But, a couple thoughts on the 315 and 35 you've called out. Another friend had one of each and took measurements. Both are "35s" (though neither is a real 35" tall, which is typical for most tire brands). But the 315s are slightly narrower than the 35s. He said about 3/4 to an inch.

Also, the 315s are available as either a C-rated or E-rated tire. The C-rated will be a more comfortable ride because they are softer. However, they are more susceptible to flats. The E-rated will ride slightly harsher, but be more resistant to flats. I've found the 315 Es to be a great tire--both on my JK and on my Gladiator. Road noise is good, even as the ones on my JK wear down to needing replacement pretty soon.

Video, in case you're interested in one of several instances where my friend experienced a flat. It's over 200 miles of very rough road to the next tire dealer. 6:46 if not forwarded automatically. We're crossing Atigun Pass ...

 

[rbishop]

That size is 11.3" wide on an 8" wide rim. Rubbing will depend on the wheel offset. I just looked at the KMC XD Rockstar III you are considering to see what the offset is, but their website says it does not fit a JT.

If they fit the JL and have the same bolt spacing pattern then they will fit the Gladiator.

 

[rbishop]

I am running Nitto Ridge Grapplers 35x12.5x17 on KMC XD137 with Offset of -6. They don't rub at all but I do have a 4.5" SkyJacker lift on my Sport. The Ridge Grapplers are expensive but they are a good ride with limited road noise.

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