After putting on my new wheels I realized I've never looked at my spare tire. I discovered that the spare tire is a 17 inch tire and my tires are 18 inch tires. I also discovered that they have a different circumference and therefore it is pretty much pointless because I won't be able to use it. I did some searches on ebay and in an effort reduce weight, I found these 00 01 02 03 04 05 LINCOLN LS SPARE TIRE WHEEL DONUT 145/80/16 OEM | eBay They have a circumference of 79 while my 18's have a circumference of 78.8. Would this cause problems within my front or rear differential, or would my diff be able to tolerate this small difference for a short amount of time? I will buy a full size tire if I really need to, but I would like to cut down on weight in the rear and I don't see me using my spare tire for much more than around 20 miles at the most. Thanks in advance for your help!

 

I guess it will be able to handle the difference till you get the car to a shop. But on the other hand - it's always a good idea to have a full size spare tire. I mean to find the same used rim and tire as you have on the car now. It costs some money, but at least you won't be worrying about the transfercase

 

It's not really about the transfer case because the transfer case would only be under pressure if the front and the rear were different sizes. I just want to know how "open" our differentials are. I know that the full sized is the way to go, but it seems like a waste of money. 150 for a tire and 200 for a wheel is $350 so I can drive 20 miles in leisure. I wish I had $350 of extra spending money, but on a high school budget, I don't have that sort of extra change. Thanks for your input however!

 

can anyone answer this question for me?

 

0.2" on circumference is only 0.065" on diameter, I wouldn't give it another thought.

 

Disguay::: If you have a good tire dealer that you frequent they should be able to fix you up at minimal cost. CASE IN POINT: I put four new tires on the Granddaughters Grand Cherokee AWD, bought road hazard for $35.00 and they threw in a correct spare for nothing with 90% tread left.They make enough on a sale and they are glad to unload a used tire plus treat you good.They recommend about 2-3 % difference front to back and side to side for any extended period such as if you were on a trip had a blow out and don't want to get ripped off at a out-of town shop.I realize you need a rim also a junk yard should have a 105mm,5 inch bolt pattern rim with a 2" center hole for cheap. $50.00 total is peanuts compared to $2000.00 transfer rebuild.

 

thanks everyone for your insight! I am going to just go with the compact spare off of the s-type because it is smaller than a 2-3% difference. Thanks to everyone for your help!