Topic: Time for tires...30 or 31's?

[Sine Deviance]

Its a Daily Driver,Im keeping this one mostly stock.I'll do some light off roading,Camp jeep with my kid, and fun in the snow. .I wasnt sure what power loss to expect going up to 31"s. Im more concerned about bieng able to cruise along at 70 mph and stay with the flow of traffic on hills. This is my 5th wrangler. My first was a 4cyl but never went bigger than 30"s. My last 3 were 6cyls so I didnt have to worry about tire size much. Is there a noticable loss of power between 30s and 31s?
thanks again for the replies!

If you're really that concerned about keeping 70mph on the hills then you will want to look into bolt-on engine upgrades. Swapping to a 4.0L throttle body from a junkyard helps alot and it's a direct bolt-on. It's also extremely cheap. A good intake also helps and you don't even need to buy one of the expensive ones. Just get a conical filter and some 3" pipe and build your own. I did both these mods and I'm out $60 altogether.

Otherwise you can basically kiss 70mph in 5th goodbye. You might be able to hang 65mph on a good flat with no headwind. On hills you WILL have to go down to 4th to maintain speed. Still, the 31s are totally worth it. I have 31 BFGs and they kick ass!

[Jeffy]

Meh - 35's and stock gearing works, you just never use high gear

The PCM doesn't care.  I'm still running the original speedo gear with my 35's

And the world is flat, huh?

[neale_rs]

For a TJ, I would say 31s.  For a YJ you may need to lift a bit or install TJ flares to fit 31s properly.

[Sine Deviance]

For a TJ, I would say 31s.  For a YJ you may need to lift a bit or install TJ flares to fit 31s properly.

Well, that's subjective. If you're building a mall-crawler and you're not planning to go offroading or otherwise put the Jeep in a high-flex situation, 31's will fit okay.

Otherwise, yeah, a 2" lift will leave you plenty of room.

[neale_rs]

Well, that's subjective. If you're building a mall-crawler and you're not planning to go offroading or otherwise put the Jeep in a high-flex situation, 31's will fit okay.

Otherwise, yeah, a 2" lift will leave you plenty of room.

Mine used to rub a lot with MT 30s (with AT 30s it was OK).  I'm talking about the rear plastic fenders getting worn down noticeably (forward part) each time it was used on even the easiest dirt roads or even just a rough paved road. It depends on the backspacing and how sagged the springs are.

[sharpxmen]

Well, that's subjective. If you're building a mall-crawler and you're not planning to go offroading or otherwise put the Jeep in a high-flex situation, 31's will fit okay.

Otherwise, yeah, a 2" lift will leave you plenty of room.

31s won't fit with stock everything under a YJ (no b/l, no shackles or springs), they will rub the flares. The stock leafs are pretty soft so going over bumps might hit in the fenders/tub as well. I had them with 2.5'' and would still rub in a few spots from what i remember

[Jeffy]

31s won't fit with stock everything under a YJ (no b/l, no shackles or springs), they will rub the flares. The stock leafs are pretty soft so going over bumps might hit in the fenders/tub as well. I had them with 2.5'' and would still rub in a few spots from what i remember

Rubbing the flares would be because of your wheel offset.  Same goes for rubbing the tub.  You can fix it by adjusting your steering and bump stops.

Like neale_rs also said, it will also depend on how saggy your leafs are.  Keep in mind that the newest YJ is 14 years old while the oldest is 23 years old.  That's a lot of miles.

[chardrc]

bds 2.5 inch lift and .75 inch lift (or was it .5) with stock Rubicon tires(31's) rub the front fender flares in realy flexy areas. with sawybar and track bars removed.

[sharpxmen]

Rubbing the flares would be because of your wheel offset.  Same goes for rubbing the tub.  You can fix it by adjusting your steering and bump stops.

Like neale_rs also said, it will also depend on how saggy your leafs are.  Keep in mind that the newest YJ is 14 years old while the oldest is 23 years old.  That's a lot of miles.

my point was that with stock suspension would rub the flares at a minimum (i had 10.5s so that's what i am thinking about) and also i don't think there's enough room to adjust the bumpstops (would hurt the travel quite a bit). i agree  about the backspacing (if that's what you meant by offset) and the steering bumps.

[Jeffy]

my point was that with stock suspension would rub the flares at a minimum (i had 10.5s so that's what i am thinking about) and also i don't think there's enough room to adjust the bumpstops (would hurt the travel quite a bit). i agree  about the backspacing (if that's what you meant by offset) and the steering bumps.

On stock wheels?  The tires should be well under the flares.

[sharpxmen]

On stock wheels?  The tires should be well under the flares.

i never had stock wheels, maybe in that case it won't rub

[Jeffy]

i never had stock wheels, maybe in that case it won't rub

Stock 15x6's tuck the tires way under the flares.  You can probably run flareless and still be OK with a smidge sticking out.

[FourbangerYJ]

And the world is flat, huh?

Just in Minn. 

[oldjeep]

Just in Minn. 

You've never heard of the great MN mountains?  (OK - even our ski areas tend to be in ravines, not on hills)