Would like to hear from those with 285's and automatic transmissions. I am debating between 35's and 285's, I know with the 35's I am going to want gears, but how are 285's with the automatic transmission?

I'm running a 2 door Rubicon with the 4:10 axles.

 

What gears do you have now?

 

Local driving is fine but on the highway the OD is way to low and kicks out quite a bit, mine is not broken in yet so I hope it gets a little better so for now I turn the OD off @ any less than 60 mph. I have 33/12.50/16 and It's not nearly bad enough for me to lay out the cash for regearing but 35's would require it. If it makes a difference I have the Swamper TRXUS mt's and they are very heavy. Hope this helps.

 

OH yea, that would be helpful, huh. It's a Rubi, so the 4:10's.

 

Abosolutely, not true.

WIth 285's it will literally feel like stock. With 35's it's a little different, but it depends on how you drive. We currently have Maxxis Bighorn 34's on our Rubicons. Here's how it drives:

Acceleration is slower, yes, but you're moving a lot of extra unsprung weight. So it does take longer but once you're moving the actual weight helps it to move. You do feel that it's heavier when braking.

On the highway, if it's not windy or hilly, it stays in overdrive no problem. When it gets really windy or hilly, I just switch the overdrive off to prevent it from searching for gears.

I run 26 psi in the front and 27 in the rear. I'm getting around 15-16 mpg. It's probably one or two miles less than stock. But, I do have to say that the ride feels ten times better due to the lower pressures.

Now, if you can live with these things, slightly slower performance (it's a Jeep not a racecar), and slightly poorer gas mileage (could have bought a Honda), you will not need to regear.

Oh, yes, almost forgot, the speedo will be under by about 10% with 35's, so you have do to the calculations accordingly.

 

If I am not mistaken those Bighorn's measure a true 34", so your saying your somewhere between the 285 and 35" in your comparison?

 

I ran 285/75 for a while and it ran very slightly slower than stock. Definatly wouldnt regear from 4:10s. I would only regear if you went bigger than 34".

 

I have an auto with 33's and 3:73 gears. It really bogs down on hills at highway speed. I just take it out of OD and it is fine. I can't tell any difference with city driving.

 

You can run 305/65R17 they are the same as 33x12.5.
I'm running 305/70R16 that are the same as 33x12.5 I'm happy with them. I have 4.10 gears. They didn't kill the perfomance totally. You can fill the difference when pulling long hills. But if i was to do it again i would put the 315/75R16(35x12.5) i plan on changing the gears in the next year or so.

 

I'm running 285/75/16 ProComp Xtreme M/T's on 16x8 soft 8's with 3.73 gears and an auto transmission

It is a little slower on take offs but I haven't had any trouble with OD. I get about 15mpg now, down from 18mpg when stock.