Tires/Tire aging - winter and spare tires
I'm the chap that emailed you back in 2008 about Bridgestone Blizak P225/70 R15 winter tire pressures on an 2001 Mazda B4000 2WD pickup truck. Today, I'm asking a couple of things related to those same tires and a spare tire on the same vehicle.
1) I still have those Blizaks that we discussed back in '08. I'm wondering if I should replace them or try to get another winter out of them?
The date code on them is 2507, telling me they're over 8 years old. I had them installed in December '08. They've still got 9/32" to 10/32" (and perhaps a wee bit more) tread depth on them. I've shown them to three local tire shops. (Actually, each tire shop really only looked at one or two of the tires). Each shop noted the amount of tread left and that the tire didn't appear to have any observable cracking. Regardless, I'm aware of the tire industry recommendation that tires >= 10 years old should be replaced, and that some tire mfrs. and auto mfrs. recommend changing them after six years of use. Still, I'm wondering if I can or even should try to get one more winter season out of them, or should I assume they've deteriorated to the point of being a safety issue (from sudden failure) based on age?
I've noticed they spin more easily on ice these past two or three winters (i.e. when starting up at an intersection and the road has a thin layer of ice) and that the rubber tread has noticeably hardened from what I recall when they were brand new (which would explain the wheels spinning on ice). I don't have any money coming in right now, so I'm faced with an obvious economic issue (at about $600 $Cdn. for a new set of winter tires), as well as a possible safety issue.
I had the Blizaks on the truck for a maximum of six months out of the year in the winter/early spring months, alternating them with some Michelin all-season tires. For the first four years, they didn't see a lot of kilometres since I didn't drive the truck too much. When on the truck, they were exposed to cold temperatures down to -35C and warm ambient temperatures up to about +15C (until I could get them swapped in the spring with the all-season tires). When not on the truck, I had them stored in a dark, unheated/outdoor U-Haul storage locker, stacked on their sides (on rims)four tires high, on top of plywood supported with 2x4's, so they weren't in direct contact with the ground/floor. Because the locker was unheated, they were exposed to warm/hot summer temperatures (occasionally up to about 30 degrees C). For the most part, the tires were stored in plastic tire bags (from the tire shop or garage that swapped tires for me) that I usually tried to seal with twist-ties. The bags eventually developed holes, so after awhile, using the twist-ties didn't seem to really matter and I couldn't be bothered getting new bags. I kept the tires inflated at 30 to 33 psi at all times.
2) My truck's spare tire is a P225/70 R15 Goodyear Eagle GA, date code 342. The date code tells me it was manufactured in 2002, making it over 13 years old. Again, tire industry wisdom says to replace the tire, but when I showed it to the various local tire shops, they all seemed to think that since it's only used as a spare, I could probably get by with keeping it as a spare for temporary use if/when needed. I had purchased the tire from a tire shop back in about 2004/2005 as a "used" tire to use to replace the OEM Firstone spare (which got put on the vehicle to replace a defective OEM tire).
The Goodyear spare looks like it has never been used (it's still got the "mold hair" on it). Since it was installed on the spare wheel rim back in '04/'05, I've never used it. It has always been stored in the spare tire well up under the truck cargo bed, so it's been out of the direct sun light, but has been exposed to extreme cold and warm/hot ambient air temperatures and moisture. I've always kept the tire inflated to 30-33 psi.
Despite the encouraging words by the various tire shops that the Goodyear spare could still serve as a temporary spare, I'm still wondering if I should replace it with either a new or a not-too-old used tire, given the tire's age? My fear is that if the tire were to be installed to replace a flat tire, it could fail under load from internal deterioration, even though it has never been used.
What say you?
First, the age of the winter tires are not a problem. The tread depth also is still good. I think you can use them for a few more years - keeping in mind, that new tires will get better traction - and that might be important to you.
Your spare: 342 means 1992! There was a changeover period from 3 digits date codes to 4 digits, and it occurred in 1999 and 2000. By 2001, it was complete, so that spare was NOT made in 2002. (Does that make sense compared to other things you know about the tire?)
Use it as a spare? I would not plan on using that tire for more than a few miles - say 10 to 20.