Spare Tire Size

[jeepguy97]

Ok here goes. I know u need to have the same size spare as your tires but how far off can it be without hurting anything? Lets say I had P225s on the jeep and had an LT235 spare would this be alright if i got a flat or does it have to be exact in order to prevent harm? Thanks in advance. I ask because I have winter tires and wheels that are 225s but summer are LT235s and i dont wanna get a flat and not be able to continue.

 

[Eagle]

Do you have a locker or limited slip?

If you run an open differential that slight difference won't matter at all. If you run a locker or limited slip, the spare should be the same size as the road wheels. You can use a spare with a slight difference in size, but with a locker it handles funny, and with a Trac-Lok you should only go a short distance because it will be constantly wearing on the clutches.

However -- even if you have a flat in the rear, you can always put the apare on the front and transfer a tire of the same diameter/size from the front to the rear.

 

[jeepguy97]

So it wont matter in the front, if they are different, because i do have a trac-lok in the back. Thanks Eagle.

 

[techno1154]

So far the two XJ's I have owned have open diffs both front and rear and came from DC with a 'donut' spear. Because I spend a lot of time on the highways and at high speed I replaced the donut with the same size tire as the other four. Come to think of it, most vehicles come from Detroit with an open diff and a donut spear; front wheel drive, rear wheel drive and four wheel drive (XJ's included). Like Eagle said, if you have a limited slip or locker them a full size spear is what you need. I go with a full size spear because I am more comfortable with it.
My $0.02

 

[willysnut]

look at it this way- factory spare size(donut) compared to factory tire 225/235-15 size! I say run it and don't worry about it!!

 

[Eagle]

A couple of years ago I picked up a bunch of donut spares out of the trash at my Jeep dealer. I use them to support some of the inactive members of "the Fleet."

They were in the trash because DaimlerChrysler had a recall to replace the donut spare on all Trac-Lok equipped Grand Cherokees with full-size spares. Seems people didn't read the fine print saying the donuts are for limited range and limited speed, and a number of irate customers wore out their Trac-Loks.