Tire & wheel upgrade on 18 JLU Sport S with 6sp (Don't know what I don't know)

[sandman2]

First time post so please be gentle!

For my daily driver, I picked up this used 18 JLU Sport S with a 6sp manual, 3:45 gears, and Dana 44 anti-spin differential rear axle. No lift. Currently has 7.5x18 take-off JK rims on it with 255 70 18 tires. I like the look of the rims so would prefer to keep those but am willing to swap those out if it gets me a larger tire without regearing.

Here's my question...Can I go with 35's without having to regear and without seeing a significant decrease in fuel economy? If not, I'm thinking I'd upgrade to the largest 33 (285 70 18) I could get without having to swap out my rims. I'm assuming no regearing at all for 33's. Correct? I will be adding 1.5" or 1.75" Spidertrax spacers either way. Am I missing something?

Don't know if the 6sp manual complicates anything related to gearing and tire size.

Any help or other suggestions would be greatly appreciated! Want to give it a beefier stance but not wanting to do a lift for mobility purposes. LIving where I do, I wouldn't be doing any crawling or significant off-roading, just mostly logging roads/trails a few times a year.

And yes, Jeeps rock in the snow!

Any pictures of similar rigs would be super helpful! Thanks in advance!

Sponsored

 

[Stuckinthesand]

If you don’t want to regear I wouldn’t go above 33’s with the manual. Most of the forum members who went to 35’s lost 6th gear. As far as gas mileage I would think a manual gets better than auto. I have 35’s on an auto and get 16 city and 19 highway.

 

[The Last Cowboy]

You can go 275/70r18 at 33.2". The problem with 18" wheels is that nearly all tire sizes above 32" are load range E.

I think if you go too far above 33", you won't like how much clutch slip the 3.45 gears will want to get going and 6th will become useless.

 

[sleeman24]

Welcome!

I had the same dilemma as you, as I also drive a manual Sahara. I decided to go with Rubicon take-off suspension and wheels (got a good deal and installed it all myself) I rarely, if ever, use 6th gear anymore. She struggles on the slightest incline on the highway so I generally leave it in 5th. I didn't lose too much in MPG and didn't need a spare tire relocation kit. For me this is the best balance of practical and style, but everyone is different.

Oh and if you like the Jeep in the snow, you'll love the KO2s.

 

[sandman2]

If you don’t want to regear I wouldn’t go above 33’s with the manual. Most of the forum members who went to 35’s lost 6th gear. As far as gas mileage I would think a manual gets better than auto. I have 35’s on an auto and get 16 city and 19 highway.

Thx! As it is, 6th gear is already pointless unless wind at your back and flat roads with no inclines.

 

[sandman2]

You can go 275/70r18 at 33.2". The problem with 18" wheels is that nearly all tire sizes above 32" are load range E.

I think if you go too far above 33", you won't like how much clutch slip the 3.45 gears will want to get going and 6th will become useless.

Thank you! Was looking into what E load range is. What is the problem with that? Doesn't that pretty much just mean it's a LT tire?

 

[sandman2]

Welcome!

I had the same dilemma as you, as I also drive a manual Sahara. I decided to go with Rubicon take-off suspension and wheels (got a good deal and installed it all myself) I rarely, if ever, use 6th gear anymore. She struggles on the slightest incline on the highway so I generally leave it in 5th. I didn't lose too much in MPG and didn't need a spare tire relocation kit. For me this is the best balance of practical and style, but everyone is different.

Oh and if you like the Jeep in the snow, you'll love the KO2s.

Thank you very much. Very nice set up you have! Do you have a lift on that or is that stock with your rubicon take offs? What size tires ya got? Really like that stance!

 

[JeepU4IA]

I have 35s with the manual trans and 3.45 gears, no problem. Yes, 6th gear is useless but was almost useless before, as you said. You would need wheel spacers and, although a lot of people do it, the 12.5 inch width of 35s are usually not approved for the stock 7.5" width wheels.

However, without a lift I would not go past 33s.

 

[Silverblkrilla]

I have a 2/1” lift now but here is my JLU on 18x9 0 offset 295/70 r18 (34x11.5) on the stock suspension. Could have left it that way but it’s a Jeep so I can’t stop adding stuff lol.
My Jeep is a 3.6 auto and i really didn’t notice the tire change outside of the look.

 

[The Last Cowboy]

Load range E is the weight rating. LT tires start at LR C and go up from there. LR E is what 3/4 and 1 ton trucks have. They have thicker sidewalls and tread and usually a different rubber compound. The ride is somewhat to significantly more harsh on a Jeep depending on which tire you choose.

 

[Djmatt85]

I ran 35s with my 6sp and 3.45s for about a year. I rarely got out of 4th gear and it was pretty sluggish on acceleration. Mpg were in the 16-17 range.

Just regeared to 4.56 and love it. 1st is a little short but I can be in 6th hitting incline and not need to downshift. Cruise at 70mph at ~2200rpm. With the limited driving I’ve done recently, it looks like I will get back 1-2 mpg.

To avoid a regear, 33s is probably where you’ll want to be. I’m sure some people are fine with 35s and the 6sp, but I feel most will eventually want to regear after going that route.

 

[The Last Cowboy]

4.56-4.88 is a good choice for 35s with a 6 speed.

 

[sleeman24]

Thank you very much. Very nice set up you have! Do you have a lift on that or is that stock with your rubicon take offs? What size tires ya got? Really like that stance!

Thanks, No lift, just Rubicon springs and shocks which added about 3/4 inch, and the tires are 285\70r17 BFG Ko2's

Sponsored