Topic: Bigger tires and drive train problems

[slazyks]

Ok I HAVE searched and read a bunch of posts about running 31s on stock suspension and engine.  This weekend I am buying some BFG mud terrain (or possibly A/T).

I'm pretty much set on 31/10.50/15.  My engine has 70,000 on it has always been well kept and never off road till I took ownership.  Needless to say it purrs like a kitten and with my 235/75/15 on it the power is great.  This is not a daily driver.  I know I will lose a lot of power going to 31s but... Will it hurt my engine, trans, transfer, diffs...?  Honestly, will this cause major premature wear?  I suppose I could settle for 30/9.50/15 mud terrains but I'm putting a Rukse 1" suspension bb on it and I think 31s will look better.

Is the difference between a 10.50 and a 9.50 wide wheel significant? How much does width matter? From the side can you even tell a difference between 30s and 31s?

I'm new in the Jeep world(obviously).  I always went on surf trips in a 2wd pu.   Most of my off road time is surfing trips deep (300-400 miles) into Baja and sometimes Big Bear and local hills/deserts around southern California. 

[grumpygy]

What are you running year would help.

  My 94 came with 31 10.50 15's when I bought it in 94.  Never had a problem with it.  It was a little down on power but not that bad.   Now with the few mods we do here, headers, throttlebody, Ignition, freerer flowing Exhaust and electric fan it runs great.

[slazyks]

It's a 2001 tj se completely stock. I would like to keep the engine stock. Minor power loss isn't a huge deal but I just don't want to compromise reliability. 

[neale_rs]

Don't worry about it, it won't cause any major problems.  Will it cause more wear?  Yes, of course (larger tires always do this to some degree), but not enough to matter much and it won't cause any sudden failures or loss of general reliability.

[jfrabat]

Don't worry about it, it won't cause any major problems.  Will it cause more wear?  Yes, of course (larger tires always do this to some degree), but not enough to matter much and it won't cause any sudden failures or loss of general reliability.

I agree...  I ran 31's for a couple of years in my '94 with stock engine, tranny and gears without issues.

[slazyks]

Thank you all for the help.  Now my only decision is mud or all terrain. I'm starting lean toward a/t because most of my wheeling is on Baja back roads.

[sharpxmen]

Thank you all for the help.  Now my only decision is mud or all terrain. I'm starting lean toward a/t because most of my wheeling is on Baja back roads.

i had 31x9.50x15 A/Ts and were horrible in the rain (GoodYear), BFG M/Ts have given me much better grip.

[neale_rs]

All terrain should be good.  I also did a lot of off-roading in 2wd many years ago, and have been in Baja a few times.  The main thing was to have two spares and tires that could hold up relatively well to the sharp rocks at speed.

[slazyks]

All terrain should be good.  I also did a lot of off-roading in 2wd many years ago, and have been in Baja a few times.  The main thing was to have two spares and tires that could hold up relatively well to the sharp rocks at speed.

By 2wd off roading I meant a Toyota Tacoma base model loaded with surfboards and supply's not actually pre-runner or anything like that.  I actually just got back from Baja on Monday night and the jeep did really good.  I was surprised actually. I never needed to dig out and it went up hills I wouldn't even have attempted in my pu. I only got 1 flat(cause unknown).  And yes I always carry 2 spares plus a plug kit.

What used to be nerve racking, stressfull driving, was actually fun almost as fun as the surfing. I was looking forward to searching out new spots. I cant believe I didn't get a jeep years ago.

[neale_rs]

We went in just some old pickups too.  But it's hard to resist speeding a bit on those long dirt roads!  I've got to make back out there some day, in a Jeep this time.

[slazyks]

We went in just some old pickups too.  But it's hard to resist speeding a bit on those long dirt roads!  I've got to make back out there some day, in a Jeep this time.

I go every couple months, whenever a big swell hits or when I just need some uncrowded waves.  You're more than welcome to join me (or us if my wife and kids go).  I usually go to the Guerrero Negro area but sometimes head further south into Baja Sur.  Cheap comida, cheap cerveza, cheap hotels right on the playa and always an adventure...nuff said.  Only setback is the expensive petrol(85 octane if you're lucky) and the terrifying 2 lane roads with one lane bridges!!!!

[neale_rs]

Thanks.  Not sure when I could go but maybe some day a chance will come up.

[grumpygy]

It's a 2001 tj se completely stock. I would like to keep the engine stock. Minor power loss isn't a huge deal but I just don't want to compromise reliability. 

  Think my power loss is more to age.  Went from 94 till 2011 before I started to make engine Mods and that was mostly cause I found this forum.

[aka-justin]

I had a 95 YJ on 31" BFG Mud-Terrians. I agree with everyone, ran a bit slower, but a few mods later, was fine. If you don't re-calibrate the speedometer, you'll trick your self in thinking you can't go as fast, but the larger tires and not regearing throws that off. Same goes for MPG. Can be fixed with re-calibration via computer, Truspeed Recalibrator, or new speedo gear, not sure for 2001. 

[mattbo505]

Before i started all my upgrades my 97 TJ came with a 2.5 suspension and 31's it did well not a huge loss in power even driving the hills in eastern Carolina. Since then i have definitely improved in the power department. Re-gearing is a must if you plan to go any bigger than 31's in my opinion. I currently run 33's and tow my 16 foot flats boat all over town. As far as the electric fan they can be installed and uninstalled in less than an hour and you can carry your old fan to throw back on if something fails with your electric. Of course the fail safe upgrades are breathing in and out which do nothing but help your engine's performance. My next upgrade will be the throttle body spacer as soon as time and money are available. Oh and one thing i have seen to make a huge difference on older high mileage engines is Marvel Mystery Oil ran some the other day after an oil change it just feels like the engine runs smoother maybe it's mental but i'm a believer.