Tire flat new versus remaining 3 treadwear

[synch22]

I did a search on tires here and didnt see an answer. 2010 hihy limited, got a flat today that cant be repaired. The shop put on my spare and sent me away no charge nice of em. Quoted me on bridgestone ecopias which I am not sold on per reviews i was able to find.

Question is remaining tires with car @20k mile had 7/32nd left per the dealer. The full size spare was brand new which i saw via some threads here puts it at 10/32nds. Am i good to leave the full size spare on or do i need to replace all tires? Just get an additional new and have 2 new rear (means i have to keep a20's longer which i wanted to swap out at some point)? Net says replace all, Tire guy says i should be ok. ANyone know?? Toyota dealer told me need to be within 3/32nd.

Whats the right answer? Toyo A20 currently on.

[fj62]

I would do the same as you except buy a spare tire that you plan to use when those crappy A20 go bald. Then you can buy 4 so that all 5 would match.

[Ralph6410]

For every 99.8 revolutions your 3 worn tires make your new one will do one less . I suspect normal variations in tire pressure and driving in less than a perfectly straight line will cause more difference.
I would wait for a good sale, replace all 4 tires with something better than the stock OEM's and use that spare back as a spare.

[05Moose]

I was looking at Costco when looking for tires last week and came across this disclaimer on replacing less than a full set. Not sure how much wear would cause the amount of difference they state. I could probably do the math, but I guess I'm just not that nice.

Four Wheel Drive And All Wheel Drive Vehicles
It is always recommended to replace tires on Four Wheel Drive and All Wheel Drive vehicles in complete sets. When purchasing less than four tires, the tire size and tread design must be identical, and the overall circumference between the old tires and the new tires must have a difference of less than 1 1/2 inches. If less than a complete set of tires is purchased, the new tires will be installed on the rear of the vehicle.

[fj62]

The last time I bought 2 snow tires for my 1995 Corolla I had to install them myself as the tire dealer would mount the tires on the rim but would not install them on the car.

The owners manual on my old 1989 all trac says 4 tires should be installed. I always used the same tires and would replace them in lots of 2 without any problems. But this was before anti lock brakes and traction control etc.

[Ralph6410]

Originally Posted by Ralph6410

For every 99.8 revolutions your 3 worn tires make your new one will do one less . I suspect normal variations in tire pressure and driving in less than a perfectly straight line will cause more difference.
I would wait for a good sale, replace all 4 tires with something better than the stock OEM's and use that spare back as a spare.

I screwed up a bit.. I assumed a nominal 29 inch diameter, There was 3/32 difference in tread (.093) My mistake was to only add the .093 to one side.. in fact it should have been doubled thus the difference in circumference is .532.