INSIDE v. OUTSIDE tire sidewall marking

Long story short, visited a tire shop down the street to mount and balance used, satisfactory, matching tires onto my second set of rims in preparation for getting new winter tires installed on my current rims next week. When picking up my wheels, I immediately noticed that one tire sidewall said OUTSIDE facing outwards, with the other three having the word INSIDE facing outwards. Brought it up to the shop manager, who insisted he is the expert and did it correctly but I could not understand any explanation through his accent. He was also insistent that specific tires be mounted on the front v. the rear, and that I would need to come back a few days later, after driving around with the wheels in the trunk, before the TPMS could be programmed.

My thought is that it’s important to have the tires facing the correct direction or else the manufacturer wouldn’t have it on the tire sidewall in inch-high capital letters! Am I misinformed about something? Can an expert tell me I am safe or not? The tires in question are Ohtsu FP0612 in size 225 45 ZR18 for a 2014 Scion tC. Info on the web indicates these are not unidirectional tires; they have asymmetric tread.

I am going to Bat Signal @CapriRacer who is a tire expert , He can give the correct answer to your question .

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Yes your are correct. The manufacturer put those words there for a reason.
Have him remount and fix it.
If you used a credit card, dispute the charge immediately. That will get his attention (one of the reasons that I always use cards. Service not good, dispute).
Also, there is a procedure to reset the TPMS sensors (do both sets of tires have sensors? If not, you’ll be driving half the year with the light on. No big deal if you check your pressure regularly, but that light has saved my butt a couple of times).

Thank you. Yes both sets of rims are OEM with OEM sensors. I know a bit about the TPMS, I’ll rant elsewhere, but I do have the tool that lets you reprogram the car’s memory when you swap between winter and summer tires. I just don’t have the tool that wakes/diagnoses/gets the sensor IDs so I am reliant on the shop for that part of it. I despise the fact that you need two separate single-purpose tools to DIY TPMS for Toyota (perhaps there is a single unit but I expect it costs several hundred bucks).

they are probably directional tires. if they are it would make a difference.


I updated my initial post to amplify that they are not unidirectional but they are asymmetrical. I was probably doing that while you were writing your reply :smiley:

If you have directional tires on your vehicle, they are simply marked by an arrow, and most of the time the word rotation, or direction of rotation, etc. Asymmetrical tires have an inside and outside to their tread . Tire manufactures will often do this to optimize the traction and wear capabilities of the tire.




Thank you. I’m about to inherit (a gift, he’s still alive) my father in law’s 2007 Tuscan. It’ll be a second car but the TPMS error light is on. Have a mechanic in the family so I’m guessing one (or more) of the batteries are dead.
Not sure if I should replace all four sensors or just take them as they go.
It’s not like you can’t drive the car if the error light goes on.
Think I’ll just fix what’s broken and take the others as they come up.
It also is going to need the whole timing belt thing (belt, water pump, tensioner, antifreeze, accessory belt) as they have never been changed (the car only has 49,000 miles I’m told. But Pop, it’s the time too that matters).

IF the light bothers you then put a piece over it and then change them when you get new tires. just keep an eye on your tire pressure. it will be cheaper in the long run if you do it when you put new tires on. just my thoughts

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I don’t know. I’m like all you guys, fanatical about car care, checked pressure every week (along with oil, antifreeze, etc) but twice I’ve had nails in my new RAV 4 and the light came on before I would have had a chance to check on the weekend.
One was a biggie.
Wife would have woken up to a flat in the morning and I would have been changing the tire to get her to work on time in the dark (by the way honey, that yellow light thingy is on again if you want to go out and take a look).

I’m all for useful information, but TPMS is often just not useful. The Toyotas like mine don’t even provide real-time tire pressure. More frustratingly, a malfunction in any one of the sensors trips the light, but there is no help about which one malfunctioned. Which leads the end user to often replace all four units, which involves unmounting and remounting and balancing all four tires and an exorbitant cost for sensors that are basically not rebuildable, can’t just replace exhausted batteries, etc. If you want to attempt DIY, you need single-purpose diagnostic equipment, usually specific to each vehicle mfr. I suppose some do it better than the way it is on Toyotas from the era I am familiar with.

In terms of my main question, I will wait for @CapriRacer, but expect that all I will say to the shop is to “please install them in accordance with the mfr instructions” which are printed on the tire sidewall…

My guess is they didn’t notice the markings on the tires and are trying to BS their way out of fixing their error.


If the tire is marked “outside” that side should be OUTside, no arguments. The tire guy screwed up, period.

If the tires are directional, they will have an arrow pointing in the direction of rotation going forward.

There have been some tires with BOTH those markings so you must buy 2 rights and 2 lefts but that is very rare. Usually one or the other.


This is really sloppy work for a tire shop, considering this is supposed to be their specialty. I wonder what other things they did sloppily, such as perhaps not tightening your lug nuts with the correct torque. They should fix this at no charge.

As for insisting that certain tires go on the back, I’m hoping that’s because those were the two with the best tread.

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Asymmetric tread designs usually have wider tread blocks on the outside for better grip while cornering.

The Uhtsu tire has minor differences in the tread, different sipes on inner/outer tread, center tread is unique. It is a cheap made in Thailand tire and likely has no asymmetric qualities, a fake.

Ignoring the inside/outside mounting reference makes an installer look foolish, also the date code is on the outside and should be visible after installation.


That is exactly what you should do. Tell him if he doesn’t do it, you’ll be forced to take your business elsewhere and you will sue him in small claims court for the cost of doing it correctly, plus you will write unfavorable reviews on every social media you can find.

Now onto the physics involved. The idea is that the outside of the tire and the inside do different things and that there is some benefit to making the tread pattern different.

Personally, I don’t think the performance difference is all that large (I don’t actually have data to back that up!) and I think the main reason tire manufacturers do it is for marketing purposes.

Update on the disposition of this event:
I returned to the shop and requested that they re-mount the tires correctly. I picked them up today, half expecting them to have been left unbalanced, but they are fine. Glad they did the right thing.

All that is left is to have the TPMS sensors paired to the car.


Ask the shop to write down the registration ID numbers so next time you can register them yourself.

Shoot, I had thought of that a while ago and it’s too late now. I would also have to go back to be sure that the ATEQ Quickset that I have will allow manual input of the sensor IDs.

Luckily, the shop that is doing my other set of rims with snow tires will take care of it for me, and from there I can download the IDs into my ATEQ Quickset for future swaps.

When I had new tires installed on my Camaro, Discount Tire did that procedure in 2 minutes. I can’t understand why they didn’t do it, or at least do it when you requested it.