Tires: can you just replace one?

juanez · #1 12-05-2006, 12:37 AM

A buddy of mine has offered to give me a set of 5 decent tires for my Wrangler for next to nothing. Here's the thing: the spare has 100% of the tread left (never touched the road). Three of the other 4 that were used have maybe 40%-50% of their tread left, but the other one is totally bald on the outside 1/3 edge. Apparently he needed an alignment.

I would like to simply take the "new" spare and use it and keep the bald tire as a spare instead, but I have heard that you can cause some problems if you replace only one tire out of an original set of 4 with a brand new one. Anyone know if this is true or just an urban legend created by Big O, Tires Plus, etc.?

FWIW, these are 33-inch BFG's that will be going on a lifted '99 Wrangler.

Ray Zee · #2 12-05-2006, 01:25 AM

people do it all the time. i personally do that stuff as well. i wouldnt put a different sized tire as that can foul things up. but just putting a newer one should be fine, but you setup would dictate how much you have changed things already and if it would now be unsafe. i would put it on the rear..

Lester B · #3 12-05-2006, 10:20 AM

[ QUOTE ]
A buddy of mine has offered to give me a set of 5 decent tires for my Wrangler for next to nothing. Here's the thing: the spare has 100% of the tread left (never touched the road). Three of the other 4 that were used have maybe 40%-50% of their tread left, but the other one is totally bald on the outside 1/3 edge. Apparently he needed an alignment.

I would like to simply take the "new" spare and use it and keep the bald tire as a spare instead, but I have heard that you can cause some problems if you replace only one tire out of an original set of 4 with a brand new one. Anyone know if this is true or just an urban legend created by Big O, Tires Plus, etc.?

FWIW, these are 33-inch BFG's that will be going on a lifted '99 Wrangler.

[/ QUOTE ]

Interesting post.

I wouldn't suggest it. I'd suggest buying three more new tires to match your spare and use the BEST of the the remaining tires for a spare.

The reason is those tires, the 33" BFG's comes with 15 - 20 mm of tread depth (even more if they are the mud terrains). When they got to where they are half worn, this changed the diameter of the tire and can cause driveaxle issues if you have tires on opposite sides of the axle that are of different diameter... Chrysler products are known for driveline issues as it is. I know 1/2" of diameter doesn't sound like a lot, but at higher speeds the difference in diameters means one tire is spinning at more RPM's than the other... and the higher speed the vehicle is travelling the worse it is for the axle.

On a regular car, especially if it is not mounted on the driveaxle of the vehicle, this makes less of a difference because the tires start with less tread to begin with.

Ricky_Bobby · #4 12-05-2006, 03:54 PM

The diameter thing is an interesting question. I really don't know if the missing tread would make enough difference to damage parts but it is possible.

However, as far as I know the only danger posed to your axles would be:

A)if you have a limited slip differential-if your tires are different diameters it will burn up the clutches in your rear-end.

B)the tire in question was mounted on your main drive axle. If you put the mismatched tire on the back you may run this risk. If it is on the front then the only time it would matter is when your hubs are locked i.e. you're in 4wd mode. Since you would only be in 4wd when off roading this really wouldn't be a concern.

It would probably drive a little funny having a mismatched tire but big mud tires like that probably ride like crap anyway.

coolhandluke · #5 12-05-2006, 07:25 PM

put the different one on the front, it will be fine.

CORed · #6 12-05-2006, 11:36 PM

It's best to replace tires four at a time or in pairs. However, a new tire, or one with decent tread, anyway, is much better than a bald one. If you're going to use four wheel drive, mismatched tires can cause some problems: Difficult shifting in and out of four wheel drive, and squirrely handling in four wheel drive may result, because with conventional four wheel drive, the front and rear axles are locked together and turn at exactly the same speed. Something has to slip, and on surfaces with good traction, quite a bit of strain can develop in the drive train. Best practice with four wheel drive is to buy 4 identical tires and rotate them.

coolhandluke · #7 12-07-2006, 02:26 AM

why would you ever ever put a jeep in four wheel drive on surfaces with good traction? you just want to waste an input shaft?

Unless you have a locker in the front, and you don't do something crazy stupid like put it in four wheel drive on dry pavement, put it on the front wheel, and you will be fine.

if you are in two wheel drive, it won't matter at all.

in 4 wheel drive (and how often do you use it?) if youre on any kind of dirt surface your spider gears will turn a little more, no big deal.

Thremp · #8 12-07-2006, 02:05 PM

Just buy a single [censored] used tire and be done with it.

CORed · #9 12-10-2006, 01:55 AM

You are of course correct that you shouldn't use four wheel drive on any non-slippery surface, but sometimes you do end up doing so briefly on a transition from snow or ice to dry pavement. Mismatched tires will often cause it to be difficult to shift out of four-wheel in these situations. Most SUV's are front-heavy and have pretty poor traction in rear-wheel drive, so you do need to use four-wheel in snowy conditions.