First, don't use a damaged or worn tire as a
spare. One day, you may need that spare and be many many miles from a
repair shop, and you'll regret the day you wanted to save a little bit of
money. You need a GOOD, reliable spare tire. Period. (And make
sure it's fully inflated before you leave on a trip.)
Second, if you're only replacing two tires, put the
new tires on the front. The front tires are your steering tires.
It's important to always have your BEST tires on the front.
Third, if the tire shop says you should replace all
4 tires, they may be doing one of three things (I'll start with the most cynical
first) -- (1) wanting to sell you 4 tires instead of 2 when you don't
*really* need 4 tires (I don't really think this), (2) they can't match the
type/tread/size of the tires you have so want to be sure you have matching tires
-- which btw, is *important* especially if you're pulling a heavy load, in poor
conditions, and mandatory if in 4WD vehicle, or (3) you actually need new
tires all the way around. Which is more than likely the case.
Personally, if you can afford it, GO FOR THE 4 NEW
TIRES. A 3/4 ton truck is a heavy vehicle. You're probably also
towing something at least some of the time. You'll save yourself a lot of
heartache, headache, flat tires, blow outs, wasted time, scraped knuckles,
worry, slow leaks, skidding on wet/icy pavement. Etc.
Can you tell I'm a tire freak? Can you also
tell I've changed a few tires in my day because I couldn't afford new tires?
<G> BTW, I always carry a small, portable air compressor to fill up
tires that can develop slow leaks. I love my air compressor!
