sounds a bit cheapskate maybe they thought nobody would notice.

That wider tyres need wider rims to operate at their best seems perfectly logical, but I can not help but think that the situation is more complex than the widest acceptable tyre simply being 2.5 x inner rim width as there are a few other variables……eg

- tyre type (The Schwalbe 2.6 Pick-up tyres used by WorldTourer look like they have very strong sidewalls)
- tyre pressure
- load on wheel
- front or rear fitment

Probably others.

For obvious reasons the ERTRO guidance is likely to be conservative.

I am currently using 26 x 2.00 Dureme and Big Apple tyres on the current 17mm internal width M717 rims on my Raven (outside ERTRO guidelines) at 35 / 40 psi minimum with no apparent problems.  I would certainly fit wider rims if and when the wheels get rebuilt due to rim wear - but I can not justify making a change until then.

Edited to add:
Just replacing the tyres on my Rudge Montigue, guess they are from the 1990s / 2000s……26 x 1.50 but so weak and flimsey!   I would certainly not trust a wider version on narrow rims.

I have an old and light cable lock from the 1970's. I doubt if anyone has that kind of key anymore and it will take a second or two longer to cut than a brake cable.

I use it for very short stops with my Brompton folders or my two lightweights in case I have to leave them in the street for a few moments, preferably when I have them in sight. If I plan a stop with any of these bikes I take a more serious and heavier lock, generally a U-lock.

My other use for the cable lock is to lock my rear panniers to the frame when doing supermarket shopping. My Ortleib panniers have the optional anti-theft wires (basically brake cables). Again, this won't stop a serious thief, but should deter an opportunist without tools.

The other family bikes have ring type frame-locks permanently fitted, these locks are fairly heavy and immobilise the bike, but a prepared thief could just pick the bike up and load it into a van and deal with the lock at leisure. I find a frame lock very convenient for short stops, but add a "serious-looking" chain lock (it isn't hard to cut with the proper tools) and/or a U-lock if I plan on leaving a bike for a significant amount of time, for example, supermarket shopping.   

I consider locks a deterrent, not a real anti-theft solution. So I have old bikes that aren't worth much that I generally use when I know I will have to leave a bike locked up somewhere. And for some trips I use a Brompton folding bike and take it with me rather than leaving a bike on the street.

That is almost exactly what I use to stop someone jumping on and riding away.  I used nicopress crimps which can not loosen.  If I park the bike for longer I use a heavier duty cable lock and the lightweight wire lock goes through the saddle and rear wheel as I have a Q/R on the saddle stem.

but Martinf in a post above is considering Andra 40 rims.

Not "considering". I'm running Andra 40 rims on one of my own bikes and on one of the bikes I maintain for a nature réserve. I agree with Andre that wide low pressure tyres should work better on wide rims.

I also have Sun Ringle Rhyno Lite rims on some of the bikes I use or maintain, these are in between Andra 30 and 40 at 22 mm internal width/29.2 external width. Got these as the widest easily available "wide" rims in France at the time.

I probably wont bother changing the Andra 30 rims on my "touring" Raven Tour, they work OK for most of the riding I do on that bike, but I dont think they are the best choice for running a wide tyre at low pressure. The Rhyno Lite rims on my "utility" Raven Tour feel better when riding on sandy surfaces, and I have used wider than 50 mm tyres on that bike.