my original spare tire....

[Huskyguy68]

Yesterday I needed to remove everything thing out of my rear cargo area/remove the cargo floor cover, remove the original spare tire .
I needed to fix/reinstall my muffler heat shield that came off and decided to drill holes in the floor board under my spare tire in order to secure the heat shield with new bolts/washers/nuts....job done.

I removed the spare tire and was surprised how good looking condition the tire was/is.
I have a 2006 Nissan Xtrail SUV ( similar to size and shape, performance of a 2006-11 Rav4.) .
The vehicle originally came with 215/65R16s All Seasons. Then I bought and had installed new Cooper AT3 Lite truck tires at 215/70R/R16s.

My old spare tire on the steel rim is 215R/65R/R16.
I took my spare tire and rolled it up beside my current tires to see what the height difference is. I used a two foot wooden handle off my windshield squeegee and laid it flat on top of the spare tire , horizontal to see how much off spare to current tires would be. I figured my 65 spare tire would sit lower then my 70 tire, but the opposite was true. Just eyeballing it with the wooden handle, my spare tire appeared to be about 1/2 inch taller.

So here are my questions: Is it because I have the weight of my vehicle on my current 215/65s/16s that the tires seem lower in height then the 70 spare tire? like ummm...unsprung weight on the spare tire. In other words, IF I were to put my 70 spare tire on as an emergency replacement tire to get me back on the road to a tire shop/garage, is it safe to drive on ? ( I briefly googled this question and it seems it seems to be safe as the tire size height is within 3% plus or minus. Some AWD vehicles may give issues to the AWD system/overheat, but I can disable my AWD with the dash dial switch.Normally rides in FWD ).
Second question is the age of the spare. I bought my SUV in 2015 and i'm either the second or third owner. When I bought the truck it had on 215/65/16 All Season tires. Eventually I put on the Cooper lite truck tires. The spare tire is a Goodyear tire, it has a more aggressive tread then a normal all season. I think it too is a lite truck tire. I once again read off Google that any spare tire that is 0ver 6-10 years old is old, dried out, unsafe to drive on.
I do plan to replace the spare tire (it is not a donut skinny tire but an actually full size tire) ......but for now, if I had to put on this old spare tire , is that very dangerous to drive on a few miles below City posted speed limit ? should I never use it and just go buy another similar sized used tire as my 215/70/16s?

 

[LouC]

That is hard to say, because it can look fine on the outside and be bad on the inside, when a steel belted radial comes apart, it gets ugly fast, the steel belt strands will beat the hell out of the bodywork, depending on how it fails. I would not use a spare that is older than 10 years, in fact this year I am going to replace a set of General Grabber AT2s on my '98 Jeep that literally look brand new, only have maybe 25,000 miles on them, but I don't think it's worth the risk. They are just turning 10 years old. That Jeep is only used for local driving but some of that is highway driving. The bias and fiberglass bias belted tires we had in the old days, when they failed they weren't as destructive as what a steel radial does. In fact I still use regular bias ply trailer tires on my boat trailer partly for that reason. We had a General radial fail on a '75 Olds Delta 88 (big full size GM vehicle) and the steel on those was super thick. The steel belts bent the lip of the fender up, when it failed!
In general steel belted radials are an improvement over bias ply tires but when they fail watch out. We had bias ply tires fail in the old days and they never did the kind of damage that steel radials can do.

There will be a date coded on the tire, it will give a 2 digit # first (that's the week of the year of production) and then 2 more digits, that is the year.

 

[AZjeff]

215/65-16 is 27" diameter, 215/70-16 is 27.85" diameter (calculated) so it's right at 3% difference.

So here are my questions: Is it because I have the weight of my vehicle on my current 215/65s/16s that the tires seem lower in height then the 70 spare tire?

Is this backwards?

No opinion on safety if used at low speeds and short distance. If you had to drive a 20 YO tire 200 miles at highways speeds to get home might be cause for concern. Then again there are "Will it start and drive home" videos on YouTube with guys driving OLD terrible looking tires hundreds of miles.

 

[ecotourist]

Two good ways to keep your full size spare tire fresh: (1) Replace the spare tire with the best tire when getting new tires, or (2) Buy 5 tires and have all 5 in the tire rotation.

 

[k1xv]

My Corvette has no spare tire. And the one around my waist is many sizes too large.