Tyres will normally have (outside) written on them on one side as the tread patterns are often not the same on the inner and outer edge as they have been designed to maximise grip whilst cornering and fuel efficiency/noise when travelling straight.
Putting them on "outside in" for these type of tyres is a no no. Swapping them from side to side does not affect the tread design as the outside tread pattern remains on the outside. However, I have always understood that it is not a good idea to change the direction of rotation for a tyre as it puts undue stress on the tyre structure.
Alex perhaps that's why most car manufacturers now tell you to change rear to front on same side to even wear on all four tyres and not from corner to corner even though outside would still be outside if you did.
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While it should be obvious that directional tyres are fitted the correct way round and they are marked as such, it does not matter regarding the date code. However all tyres are meant to be fitted with the date showing on the outside but only for convenience of reading it.
The reason for the date being on one side is, first it's changed every week so once per pair of dies is cheaper, but second, it's also very much easier, quicker and safer to fit to the the bottom more easily accessible very hot die!
Surely all this talk about directional tyres is irrelevant.
C or Commercial tyres are what are fitted to caravans, not directional or asymmetric tyres that are used on performance cars.
No they are 165/80/R13, 91/89 load index, 91 is for normal single tyre use or downgraded to 89 for duel wheel setups. Ie the twin wheel Transit pickups.
C grade Commercial tyres don't show the '80' aspect ratio unless it is other than the now standard 80%. Also the speed rating is a letter.
Histrionically, when crossply gave way to radials, crossplys were always 100% aspect ration, radials though were originally 85%. When radials began to drop to 80%, 80 was then added to the size to distinguish between them.
There are still many otherwise the same size radials made marked either with or without the 80
Today and while those tyres not marked with '80' can be assumed to be still 80, they also have a different load index because of a different construction, so 80 is still present or absent to visually show up a difference.
Why then online sellers then lump all together by demanding 80 when it's not shown on the tyre being replaced? is anyone's guess