Spare tire use

[JMOB]

I have my spare tire on right now and it feels like the auto 4x4 is kicking in when I start to coast from 65 to 60 and 45 to 40MPH. Its on the drivers side rear wheel. I have heard it would be better to have it on the front? I am trying to milk this tire out because I am getting married next weekend and our house will be built in a month so cash is a little tight for the next month. Any ideas?

04 Eddie Bauer V8 and the spare is original BFG. The rest of the tires are goodyear wrangler silent armor. All of the tires are 245/65R17 size.

Thanks!

 

[buckwill]

two things all tire brands are not same sixe even tho numbers may be same,, is it same size around,??? it might be better if u moved it to the front,,same side, just swap front to rear, front usually isnt as sensitive to minor (minor)differences,

 

[leftlane36]

I do know that running a mismatched sized tire on these Exs is not a good thing. I understand the being in a bind thing, so I would try to keep the mileage to a minimum if I were you. It only takes about a 1/4 in. size difference to make the system think there is slippage and attempt to engage 4wd.

 

[Exproblems]

I have my spare tire on right now and it feels like the auto 4x4 is kicking in when I start to coast from 65 to 60 and 45 to 40MPH. Its on the drivers side rear wheel. I have heard it would be better to have it on the front? I am trying to milk this tire out because I am getting married next weekend and our house will be built in a month so cash is a little tight for the next month. Any ideas?

04 Eddie Bauer V8 and the spare is original BFG. The rest of the tires are goodyear wrangler silent armor. All of the tires are 245/65R17 size.

Thanks!

The spare is most likely the source of your problem with the auto 4x4 kicking in. Probably has a difference in tread depth over the other tires on the vehicle. Try pulling fuses #17 & #18, this should disable the auto 4x4 system till you can get a correct depth or size 4th tire then re-install the fuses at that time.

 

[JoshMcMadMac]

Have you checked the tire pressure?

Differentials do not like any variation between tires, as the job of the differential is to spin both tires at the same speed. One tire being even slightly different than the other can tear things up. I know you are tight on cash, but it will be much cheaper to take care of the tire than to rebuild the rearend.

 

[tower]

If you are just tring to get by for a month or two unplug the 4x4 control box or pull the fuses, you wont have 4 wheel drive but this time of year it should not matter even in WI. You could also do the brown wire mod.

 

[HiImBrian]

Have you checked the tire pressure?

Differentials do not like any variation between tires, as the job of the differential is to spin both tires at the same speed. One tire being even slightly different than the other can tear things up. I know you are tight on cash, but it will be much cheaper to take care of the tire than to rebuild the rearend.

I agree, however I thought the point of the differential was to allow the tires to rotate at DIFFERENT speeds to help increase traction and limit wheel slip (ie. limited slip); requiring a locker to rotate them at the same speed. :idunno:

 

[buckwill]

thats why moving it to the front will relieve some that hunting, our diffs are not made to be cobstantly turning at diff rates, the spiders have no bearings in thm, move the tire to the front and gitr rid of all the bother till u can replace it, u dont have to unplug anything, nd making the electronics not see the diffrent rotation rate does not take away the potential damage running two even slightly diffrent tire sizes can do,

 

[jrford]

its not the diff thats complaining but the ABS sensors, they track mph for each tire. If the ABS sees a different speed for one wheel it might be tricked in thinking that wheel is slipping. Without ABS a open differential can handle different size tires/treads without any issue. Closed or LSD can to for limited time, but over the long run the clutch packs are going to wear faster and/or heat up.

the owners manual actually recommends you buy 4 tires if the others are really worn down and you have to replace one.

I use a 5 tire rotation to avoid that, if i lose one tire i can switch to a 4 tire rotation with out affecting anything.

 

[Exproblems]

A open differential can handle different size tires/treads without any issue. .

So what you are saying here is, the auto 4x4 system "will not" kick in if you have an "open diff" and have to use a spare tire of a different size or tread depth than the other 3 tires on the vehicle? Am I reading this right? My Ex has an open diff and it would be good to know for sure in case the situation ever arises to where I need to throw on the spare tire for a short period of time.

 

[Ronin8002]

I think he's saying that if you have auto 4x4 in your vehicle, it will kick in due to the different tire sizes. A 2wd explorer with an open diff could handle it. A limited slip diff can get extra wear from a different sized tire on each end of it.

 

[tower]

Guys we now have 2 things we are talking about.

One is the possibility of damage to the diff. If you run different size tires on an axle with a LS or "posi tracton" diff then you could and most likely would damage it as it would try to get both tires to spin at the same speed. An open or "regular" diff would not do this and would not be a problem.

I always liked Marisa Tomei's explanation

http://www.youtube.com/watch?v=vfgTWY_h-1o&feature=related

The other problem and the one the OP is having is the computer (by way of the ABS speed sensors) is seeing a wheel turning at a different speed then the rest and "thinking" that you have lost traction so it engages the transfer case sending power to the front axle.

If the op has a LS diff then put the spare on the front and disconnect the 4x4 by one of the methods already mentioned, if the rear is an open diff then just disconnect the 4x4.

As an option you could just put the tire on the front there is a good chance that that will solve your problem as the computer MAY not care as much if one front tire is turning at a slightly different speed as it is not normally powered. I don't know if this will work on an ex but it would be worth a shot as you would still have your 4x4.

All of this means nothing if you have AWD, if you do and run different size tires you will destroy you transfer case in short order.