RB04Av

Great idea in principle; however, on at least some of these trucks, the spare is a different size wheel from the 4 that are in service. My factory wheels for example are 17" but the factory spare wheel is 16".

_zebra

iTrader: (5)

worth it.
my dodge came with 285/60-20s & a 275/70-18 spare... i've now got five 295/70-18s with the spare on a matching wheel with TPMS. that's how i keep it cycled through when i do my rotations - it'd look stupid running a plain-jane steelie with the rest of my aftermarket wheels (or even stock wheels for that matter). wife's hummer came with a matching spare from the factory, and thankfully the previous owner wasn't a cheapskate and bought all 5 when he changed wheels.

_zebra

iTrader: (5)

OEMs include a spare on the cheapest wheel option they can just because it saves them money - not because it does anything to help the owners. if you want to maximize the life of even a stock wheel/tire setup, the best option is to match your spare to what you run. that way it ain't just dead weight.

Marky Dissod

The size of the wheel is IRRELEVANT.
How can either the speedometer or the differential possibly be able to tell the difference between 265/75R16 and 265/70R17 and 265/65R18? They're all 31.6" tall.

RB04Av

Kinda hard to buy 5 identical tires and put em 4 wheels of one dia and one of another and rotate all 5 like was proposed and about which I was responding. Although some vehicles can do that with the factory parts; my YF's 05 CR-V for example has 5 identical wheels. Butt not my truck.

You're right though as far as the speedo and the rear, OD ultimately is all that matters to those.

_zebra

iTrader: (5)

correct: consistent OD among them all is the most-important point to ensure, so if you buy a non-standard size for the runners (like jumping to 35s), ensure you get an equivalent OD spare tire for whatever wheel you use.

the most practical & useful situation is to have a matching spare wheel & tire so that you can keep it in normal circulation. otherwise, if you only keep a dissimilar wheel with the same OD as a backup, then it stays at its original diameter as the others wear down & eventually results in the same problem. say yours start out at 19/32" tread depth & you eventually get a flat after they've worn down to 5/32"... that's now a 28/32" OD difference, which is like putting a 33" spare on with 32s! if you never need that spare... well then you've just bought & never used that tire while replacing the other four 20% earlier than you could've had you circulated the spare.

Jeff71

What's this spare you guys are talking about?

I'm sure I'll now have a blow out on the way to work tomorrow...