Replace spare tire when upgrading tires?

[RideWithYanu]

First of all, let me make it very clear that my intention has never been, nor is it now, to create any kind of controversy. I should also mention that I don't speak English and I'm using Google Translate, so there might be some misunderstandings in the translation. My intention is always to contribute, and that's what my comment was about. I know very well how a Torsen differential works. It's a completely mechanical differential that uses its gears to distribute torque between the wheels. In practice, what it does is, if one wheel slips, it transmits all the power to the other wheel to prevent us from losing traction on that axle. Up to that point, I completely agree with what you're saying. However, if one wheel is smaller (in this particular case, the difference isn't significant), but if it were, the fact that it's smaller doesn't mean it will slip on asphalt. It will grip the road with the same force as the other three wheels, and that's where the Torsen system will suffer. No wheel will skid or lose traction; they simply have a different turning radius, which could compromise the integrity of the system. System. Having said that, I'll end my participation in this thread, and as you rightly say, everyone should do what they think is best. Regards, friends.

You’re good man, and you’re correct. Spare tire should always match the same size. It’s a dumb thing for anyone to try to save a few bucks on.

 

[Bad1975]

I'd go with matching, the way the skid control ECU works it will always be receiving a signal from the ABS wheel speed sensor that one tire is rotating faster (slipping), there may be a threshold before it acts but that is unknown? Think of the worse case where you need to use the spare, snow, mud or even a downpour or when fully locked off road is it worth saving a few bucks to possibly be stranded because the skid control ECU and ABS system to function as it should and helped to put you in the ditch or cause an accident or you were locked and now can't get unlocked?

What I can say from experience is on a part time system a smaller spare when fitted while 4WD is engaged will not allow you to come out of 4WD and I have since always ran a full size spare as I got to limp 20 miles on pavement with the ABS system freaking out and with 4WD drive engaged. That spare was toast when I arrived at safe place to leave the truck unattended overnight as it would lock up every 20-30 feet and leave a drag mark on the shoulder for ~10 feet. Admittedly the spare was 28" and the other three were 33" so quite a big difference. Spent the entire next two days being driven around by my buddy looking for a new tire near where we were camped for hunting so I could drive back home 300 miles two days later. Worst hunting trip ever!

I'd venture to say if locked on this platform there is good chance your staying locked or will have an even more difficult time getting unlocked than already is normal.

 

[Kevin]

Update: I purchased 5 new Michelin Defender LTX MS2 in 255/70/18 for my 1958 LC. Discount tire will do a 5-tire rotation for free with the spare if requested. That will accomplish two things; keep the tires the same size as they wear and also add about 20-25% to the lifetime service mileage for the set.

Snow traction is much improved over the OEM Yokohama Geolander tires.