I have been meaning to ask the dealership this question for a long time, but I always forget to when I'm there. The sad thing is I will probably get a more direct and truthful answer here(no offense to any forum members that work at the dealership) . I have the 6mt with all wheel drive and I have upgraded my tires from stock(265/70/17) to a larger tire(305/70/17), but I only bought 4 I still have the stock tire for a spare. Can I use that spare tire in an emergency situation. I pretty much have ruled out using it but I'm curious if its possible to use without doing damage to the all wheel drive. But the real question I have is if I buy 5 brand new tires go for 30k to 40k then get a flat can I run the still new spare tire because it will have a slightly larger diameter?
I have a lot of friends and family members who own Subaru's and they have found out if they have a set of tires with 20k or more miles on them and they pop one, they have to buy 4 new tires. Having one slightly larger tire destroys the all wheel drive system. The funny thing is, the older Subaru's (I don't know if they still do this) came with a small donut as a spare. What the dealership didn't tell people is if they have to use the spare there is a button in or behind the glove box that will shut off the all wheel drive so you can run the spare. Needless to say people would get a flat, put the spare on, not knowing about the switch and drive off. They would literately drive 10 to 15 miles before total failure of the all wheel drive and have to call a tow truck.
Does anyone know if Toyota's all wheel drive system is as sensitive as Subaru's. I just want to know for future reference.
I don't know about the sensitivity of the all wheel drive system, but I would recommend that you buy a spare that matches your other four tires. The toyota manual recommends a 5 tire rotation, so the tire tread depth should not be too far off from the other tires.
No, I wouldn't even consider it unless you are in a very serious situation were you need to get some where. IE some one is dieing and you need to get them to help but you get a flat why leaving the dirt to the pavement, then I would.
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Last edited by jeshua : 08-23-2007 at 11:17 AM.
Reason: spelling
Don't do it. You will burn up your t-case. Same goes for any vehicle with a limited slip in the rear like my truck. I have to run the spare on one of the front tires because I can burn up my rear differential if I run the the spare because my spare is smaller.
I'm not a mechanical engineer, but all of the differentials on the 6MT are open unless you lock the center and rear differentials. I can't see how it would be a problem if the differentials are unlocked.
One easy way to find out. Put the spare on and drive around the block. If the VSC light comes on or the truck beeps at you then there is a problem. If not, then everything should be fine.
The tires are 7% different in circumference. That's a lot less than the difference with a standard tire and a "donut" spare.
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I'm not a mechanical engineer, but all of the differentials on the 6MT are open unless you lock the center and rear differentials. I can't see how it would be a problem if the differentials are unlocked.
Use the smaller spare only in an emergency just to get the big tire fixed. Don't put it in HL or LL. You will stress the center torsen diff by making it think that your'e slipping all the time, so keep speeds real low and avoid highways. Then you might be fine.
In regular driving in HH. the center diff is open. The rear diff has an electronic locker that you have to activate. The Atrac also has to be activated before it starts its braking deal due to spinning and potential tire differences that it could read as a spinning tire. As far as any problems, I have no idea.... I would always have the same sized spare as the rest of the tires for my own peice of mind.
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. I have the 6mt with all wheel drive and I have upgraded my tires from stock(265/70/17) to a larger tire(305/70/17), but I only bought 4 I still have the stock tire for a spare. Can I use that spare tire in an emergency situation. I pretty much have ruled out using it but I'm curious if its possible to use without doing damage to the all wheel drive. But the real question I have is if I buy 5 brand new tires go for 30k to 40k then get a flat can I run the still new spare tire because it will have a slightly larger diameter? 
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