285/75/r17 on stock JL Sport

[IamThad72]

So if you put those tires on, without all the other accessories, would you still need the spacer? I'm thinking about that tire size for my 2020 Willys and just getting the high top fender kit from mopar. Thoughts?

Nice looking Jeep. White was my second favorite color.

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[McCoys]

So if you put those tires on, without all the other accessories, would you still need the spacer? I'm thinking about that tire size for my 2020 Willys and just getting the high top fender kit from mopar. Thoughts?

You don't need it but ideally, you should have it.

I've measured my sag from stock. Currently I have 5 inch front wheel well clearance to fender and 6 inches in the rear. If I was stock without spacers or accessories, I would have 4.25 inches in the front and 5 inches in the rear.

IMO, you may potentially hit the the fenders if you flex too hard, too fast on 34s. Easiest way to tell and I'm surprised most people on this thread haven't realized is simply do 3 things.

1. Find actual tire size - In my nitto case, its marked 33.8 inches but true height is 33 inches
2. Measure bump stop travel length on stock
3. Take 33-31 (stock true size) = 2 inches and divide that by 2 = 1 inch which is your added tire height into the wheel well. Next, compare bump stop to axle bump plate travel. If your remaining wheel well travel is greater than bump stop travel, then it will fit. If it is less than current bump stop travel then it won't fit. Simple as that.

I guarantee you this is the optimal sure-proof steps to ensure that you get the optimal size tire for your clearance.

 

[iniezen]

Awesome thread, almost ready to pull the trigger on this tire size for my Sport (3.6 automatic). Do any of you feel like you need to re-gear for this tire size up from the 3.45 gears? Specially those of you who live in California or other hilly terrains? Are most of you not losing any gears with these tires? Thank you so much!!

 

[DougJaneway]

Awesome thread, almost ready to pull the trigger on this tire size for my Sport (3.6 automatic). Do any of you feel like you need to re-gear for this tire size up from the 3.45 gears? Specially those of you who live in California or other hilly terrains? Are most of you not losing any gears with these tires? Thank you so much!!

I'm in hilly East Tennessee and the only time I ever notice it is above 70 mph on a hilly highway. It'll hunt between 7-8th a little but not bad. I also have the lightest tire in the size though with the Cooper AT3 ATX.

 

[McCoys]

Awesome thread, almost ready to pull the trigger on this tire size for my Sport (3.6 automatic). Do any of you feel like you need to re-gear for this tire size up from the 3.45 gears? Specially those of you who live in California or other hilly terrains? Are most of you not losing any gears with these tires? Thank you so much!!

The trick to figuring your ideal gear ratio for tire size is take your desired tire size and multiply that by your current final gear ratio which is 3.45 and then divide that by your current tire size.

example: 35 x 3.45 / 32 = 3.77.

nobody makes 3.77 for dana 35/30 so you can’t regear unless im missing something. You also sure as hell dont want to regear to 4.10 unless you’re going 37s. At that point, you should have swapped to dana 60 anyways

 

[DougJaneway]

The trick to figuring your ideal gear ratio for tire size is take your desired tire size and multiply that by your current final gear ratio which is 3.45 and then divide that by your current tire size.

example: 35 x 3.45 / 32 = 3.77.

nobody makes 3.77 for dana 35/30 so you can’t regear unless im missing something. You also sure as hell dont want to regear to 4.10 unless you’re going 37s. At that point, you should have swapped to dana 60 anyways

I'm sorry, but that's bullcrap. The Rubicon has 4.10 gearing in a smaller tire size. 4.10s would be pretty perfect IMO.

 

[McCoys]

I'm sorry, but that's bullcrap. The Rubicon has 4.10 gearing in a smaller tire size. 4.10s would be pretty perfect IMO.

He is on a sport and i’m assuming he wants to keep his current ride and feel.

attached is the chart for gear ratios. Hence i said what I said

 

[DougJaneway]

He is on a sport and i’m assuming he wants to keep his current ride and feel.

attached is the chart for gear ratios. Hence i said what I said

Even according to that chart it's going to be right in the center of daily driver and best overall performance in 4.10 gearing. Also, the way the transmission is, you'll get more use of 8th gear on the highway which will probably net overall better MPGs.

 

[bajanut]

I also want to add, on the trip back, i did add a 100 pound girlfriend in the car with me on the trip home to Seattle, was picking her up in portland.. not sure if the 100 pound difference made that much of an impact on MPG, But still wanted to mention it

did you take in consideration the larger diameter? did you flash the new tire size? because of the larger diameter it would read less miles traveled as compared to stock tires

 

[iniezen]

Thanks. I see a lot of posts about people on 33s being fine without re-gearing, and people on 35s wishing they had re-geared. This is one of the few threads I've seen about 34s, but saw little to no mention of regearing. This is my daily driver in Southern California but I want to wheel it (not too crazy) and drive it up the mountain roads without messing up my transmission too bad. Thanks!

 

[McCoys]

Even according to that chart it's going to be right in the center of daily driver and best overall performance in 4.10 gearing. Also, the way the transmission is, you'll get more use of 8th gear on the highway which will probably net overall better MPGs.

i disagree on better fuel economy. 7th and 8th is such a small difference even at 70mph. If anything, he is hitting 8th at a much lower speed if he regears to 4.10. I just don’t see the point in spending $2000 to regear to go up to 35s. Also depends on whats hes doing, is he really crawling? Either way, he shouldn’t be going to 37s on dana 30/35s.

 

[DougJaneway]

did you take in consideration the larger diameter? did you flash the new tire size? because of the larger diameter it would read less miles traveled as compared to stock tires

i disagree on better fuel economy. 7th and 8th is such a small difference even at 70mph. If anything, he is hitting 8th at a much lower speed if he regears to 4.10. I just don’t see the point in spending $2000 to regear to go up to 35s. Also depends on whats hes doing, is he really crawling? Either way, he shouldn’t be going to 37s on dana 30/35s.

I agree there. I'm running on stock gears and I'm having no issues. I will probably re gear eventually because I tow a boat with it and I plan to put on a slight lift and steel bumpers but it's definitely not necessary. I just like that low end torque.

 

[blnewt]

Thanks. I see a lot of posts about people on 33s being fine without re-gearing, and people on 35s wishing they had re-geared. This is one of the few threads I've seen about 34s, but saw little to no mention of regearing. This is my daily driver in Southern California but I want to wheel it (not too crazy) and drive it up the mountain roads without messing up my transmission too bad. Thanks!

The 285/75 is probably going to be my next tire size. I currently run 295/70s (33.3" tall) and didn't lose much w/ the 8AT. I wouldn't want to go to a full 35 or even a 315/70 though as that extra tax on the 3:45 gears isn't something I'm wanting to do. Also that 285 width is perfect w/ my 8.5 +10 offset wheels and the Rubicon suspension swap is just right for a 34 but would probably need small spacers w/ anything taller than 34s.

 

[kantho]

Awesome thread, almost ready to pull the trigger on this tire size for my Sport (3.6 automatic). Do any of you feel like you need to re-gear for this tire size up from the 3.45 gears? Specially those of you who live in California or other hilly terrains? Are most of you not losing any gears with these tires? Thank you so much!!

I am quite happy with the power of my Sport 3.6 with 285/75 r 17 tires. I didn't wish to re-gear and am comfortable going 72 mph in 8th when on a level road. Not sure though how much impact the added weight of 4 door would make. My friend with a JLRU drove my 2 door and was impressed/surprised with the power.

 

[Red Rock N Roll]

Good looking JLU! I did the same thing with my 2018 going from stock Goodyear Wranglers to some BF Goodrich AT KO2's 285 70R 17s on Jeep Moab stock wheels that I had on my first 2011 Rubicon. Putting a 2.5" Teraflex base kit on mine on the 21st

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