I have come across 230cm abrasive wheels with no expiry dates on them. Other markings seem ok on them, am I correct in thinking there are supposed to be expiry dates marked on them?

Generally the date of manufacture is printed on the disc . HSG 17 states 3 years from the date of manufacture. This would be assuming the discs are kept in good condition and free from contaminants

I took this up with my abrasive wheel supplier, we get them direct from the manufacturer.
The blanket 3 years is NOT true, it depends upon the construction and make up of the wheel.
Storage conditions will also have an affect.
However, many types of wheel will last much longer than 3 years if stored according to manufacturers guidance. Some indefinitely.
You need to be sure that the wheel compostition has an expiry, not all do.

Paul

Roberts22341,
Why would you have a strengthening ring on an abrasive wheel?

This is not a requirement of all abrasive wheels as per my previous comment that an expiry date is not necessary on all abrasive wheels.

All,
Please do not make generalisations about abrasive wheels based on the experiences of reinforced bonded cut off wheels, grinding wheels for angle grinders etc.
(Not exhaustive).
There are thousands of different types of wheels and these types only make up a small portion.

I have personally mounted 42" diameter wheels, 6 to a spindle, there was not and still would not be an expiry date on these!

Paul

Please excuse any spelling/typo's, no spell checker and its late!