16" Spare with 17" on truck

So, I changed to 17" XD wheels soon after I bought my 2017 SR5. Now have a little over 50K on the 17" Nitto's put on the 17" wheels and, soon will be buying new tires. Not to mention the tires - including the stock spare - are now about 7-1/2 years old. Just due to the age I'm considering replacing the never used spare.

Question: If/when I do have to use the spare, would there be any problem putting the 16" on one wheel while all others are 17"? I would hope it would only be for a very short distance of use before I could get the flat repaired/replaced but, you never know what the situation might be.

Should I change the spare to a 17" wheel & tire?

 

Some will reccomend a full size matching spare. In emergency situations, mismatched sizes are fine. Your truck has open differentials. Won't hurt anything. Of course I wouldn't reccomend driving across the country on it, but driving to a repair shop would be absolutely fine. You may throw an ABS code for mismatched wheel speed but it won't hurt anything. I however, am some of those people that reccomend just getting a matching size spare wheel and tires. Doesn't have to be the same look/brand just the same size. Should be able to find a fairly cheap combination.

 

I would like to add that another benefit of having a matching spare is that you can do a 5 tire rotation so you get the most life out of all tires instead of having a spare that may never get touched.

 

Definitely better than no spare at all. Just minimize the last minute runs to Vegas with it on.

 

Not sure I agree with above.

First; the size of the rim is not the concern. It is the overall diameter of the tire. This determines the distance (the tires circumference) that the tire travels over 1 revolution.

Think about it in extremes, for example, a tire that has a diameter of 1", which travels 3.14" every revolution. Imagine that against a tire that has a diameter of 100", which will travel 314" per revolution.

A larger aftermarket tire, paired with a stock sized spare, on the same vehicle, while not as extreme as the example above, follows the exact same principle and will travel different distances per rotation as you drive down the road.

This is precisely what your vehicle stability system checks, via the ABS sensors, constantly, likely ~100x per second, every second, as you drive.

I wouldn't be surprised if the truck tries to compensate for this difference in wheel speed in some way. I don't have first hand experience, but these trucks are smart nowadays.

Every single knowledgeable person I know purchases a matching sized spare when upgrading tires.

If you can't afford to buy 5 tires at a time, you shouldn't upgrade until you can afford all 5, IMHO.

 

If the trucks tires are 265-70-17 and the spare is 265-75-16 they will both be the same diameter. Check out the tire size calculator on the left side of the home page.

 

Even if everything you just said is true, you appear to be ignoring the fact that a spare is designed to get you to the tire store. A short drive with one tire being down one size is not going to hurt a damn thing.

 

Haha. Must have missed the ~100x per second part. And Toyota is denying warranty claims when people offroad their 'Offroad' trucks.

But sure, sure. They definitely designed their vehicle to accommodate those with aftermarket tires and stock sized spares.

I can agree with you that a single size may not cause any issues. But OP did not specify his aftermarket tire size. He could be on 33's or 35's on his 17" rims. Definitely more than a single size.

 

I think the spare size doesn’t matter for short periods. Remember the donut spares to reduce weight? A spare is exactly what it says (spare).
If you want a five tire rotation I wouldn’t do it since most tires are mounted for right or left side. Due to the tread pattern. So. Spare who cares just don’t run on it long or fast

 

I like that you wrote a lot of words that were already covered and your only actual concern is "maybe the truck will do something i dunno lol". Also, the ABS sensor isn't "checking 100x a second". The Tacoma uses active ABS sensors that output a constant current that represents a magnetic force generated by a disk in the hub.

Truck has open diffs. You'll be fine to get to a shop to get a better solution. Optimally it would match but it isn't the end of the world if it doesn't. Don't put it in 4WD or lock it. If you wanted to be safe while using the 16" rim you could buy a larger tire for the 16 rim so that the overall tire diameter matches.

 

This is all that matters!
Rim size doesn't matter.
Offset can play a factor with drivability.
But for a spare should be fine to get you home.

 

Lol, this is just silly. I suppose unless you are speaking in massively broad terms, or you assume that I should know what people will type up in posts after me.

I don't speak in absolutes, unless I am 100% sure of something, hence the comment that there may possibly be an issue.

With everything set aside, the OP simply asked if he should get a matching sized spare. And my personal recommendation is that he should.

Where I am at right now, this very moment, the nearest Discount Tire is 126 miles from me. And they can't get me a matching tire for 6 business days.

But sure, let's assume that OP will need a new tire when he is in the parking lot of the tire shop, and that they have one on hand for him.

And what does an active ABS sensor have to do with disproving my comment about how often it checks wheel speed? Do you really know what an active ABS sensor is? Or how it functions?

Something tells me that you don't truly grasp it, as you have edited that portion of your post three times since you posted it. I could dissect it for you, but it isn't worth the effort. I'll just say that it's silly to assume that because something outputs a constant signal that it can't be checked however many times per second or minute or hour that the device receiving the signal wants to check it. Hell, with a constant output, a computer could check for variations 100,000 times per second if it wanted to.

Edit: make that 4 edits to that portion of your post.

 

If you think that there is active checking interval involved in a transducer producing output generated from a magnetic disk on a wheel and that the interval is anything other than the tires rotational speed, I have a bridge to sell you. (Edit for clarity because I sense your desire to nit on this point rather than stick to the topic: if you think that the interval could somehow be greater than the tires rotational speed).

But no, I was simply pointing out the fact that you wrote a lot of words with no actual substance at all. Your entire post can be boiled down to some condescension about tire rotation and "maybe it does something that I can't articulate even vaguely". That last part is really the only part that matters. If you can add any form of substance to that concern, it might be a worthwhile reply.

OP won't have any issues with ABS or the LSD if the wheel speed sensors don't match. ABS sensors fail or are damaged (or removed entirely by people upgrading their axles) all the time and the truck doesn't suddenly just like, start slamming on one brake or whatever scenario you've conjured up in your mind. You might throw a code. If you put the spare on the front and you pop it into 4WD, you risk damage. If you put the spare on the rear and you engage the rear locker, you risk damage. If you do neither of those things and drive 126 miles to the nearest Discount Tire, you will be fine.

EDIT: and the edits were to warn OP not to use 4WD/ERL because that will actually cause damage and then to suggest that they maybe just buy a larger tire for the smaller rim if they just want to save the rim $$.

 

I just wouldn’t use 4wd or the locker with it.

 

You'll be fine running the 16" spare. Functionally there will be zero issues. Changing to an alloy can save some weight though, at which point you might as well step up to 17".

 

Thinking about your spare and it's general condition are a good thing. Nothing worse then needing it, and it is no good because it rotted away under the truck. Most Tacomas come with a 16" spare regardless of what wheels size is on the trucks. Early 3rd gens had 17" spares on trucks with 17's, ( My 2017 TRD Sport had a 17" spare. ) so changing to match is a personal preference. As long as the Revolutions per Mile spec is close to the tires for everyday driving, rim size make no difference.

I stepped up a size on my truck and decided that I would do the spare as well. So I have a brand new 265/70R17 Toyo Open Country AT III on a factory FJ 17" spare steel rim.

 

You don’t need to match the wheel size, just the overall diameter of the tire.

 

I wouldn't replace it. Chances are you may never need it!

 

Why cheap out with tires and your rig? Even if it is just a "short" distance why not have a proper safte replacement to finish your trip and comfort knowing you do not have to concern yourself with getting a replacement(s) right away. You can take your time to make a decision, order tires, etc. I traded my 16 steel rim spare rim straight up for a 17" alloy takeoff (minor scuffing) from my dealers Accessories Dept (they had many) and paid them $60 for a used 17" Sport tire take-off as well.

 

If you're not exactly sure, or you know for a fact, that your spare tire is a different diameter, then make sure it's on the front in 2wd. That way, the drive tires match in the rear.

I dunno. Maybe that's pure BS, and only worked in the days when we had locking hubs. Can someone pass me a beer? This campfire sure is nice...

Also, if you have a big brake kit, then you'll need to go with a 17" spare for sure.