larger rear tire

[ingobohn_imp]

I can only speak for the German market, but here are rear tires in 160/60 dimension available from Bridgestone (BT23, T30) and they are officially released and technically approved for the CB 1100. These tire dimensions are mounted onto the stock rims.

Ingobohn..what does " technically approved" mean? By Honda or by Bridgestone? Or is it a governmental thing.

Ingobohn..what does " technically approved" mean? By Honda or by Bridgestone? Or is it a governmental thing. Well, this is very special here in Germany.
In former times, a bike had a so called "tire binding" which means that the bike was only allowed to ride with specially "released" tires. The tires (brand, tire model, size, speed limit etc.) was stated in the "papers" (vehicle registration) which each drivers has always to carry with him. In case a police checks the bike and recognizes that the bikes uses other tires than stated in the docs, the driver was fined. When an accident happened and the insurance company showed that the accident could be fully or partly avoided with regular tires, the insurance can reject paying the bills.
So for example, if the papers state that tires from brand A (model 01), brand B (model 07) and brand C (model 11) are released, you were not allowed to use any kind of tires of brand D, E, ...
And even from brand a, B or C you were not allowed to use model 02, model 08 or model 12, and so on. It was really a pity. Especially, when you just hat 1 or 2 tires stated "in the papers", so you had very limited choice. And when the tire manufacturers deprecated producing the models which are for you, you had a massive problem. Then you had to do a check at the local technical governmental authority and show that this and that tire is also safe. But this was hard to do and cost lots of bucks.

Nowadays it changed (a bit), there is no more "tire binding" for newer bikes (the old ones still have). Now it is simple stick to the dimension and speed limit. E.g. for my CB 1100 I have front tires 110/80RM/C58V (V means up to speed limit of 240 km/h, 58 means a load index of 236 kg) and rear tires 140/70R18M/C67V.
But in the road regulation laws there is still a kind of fuzzy paragraph which says that even with the right dimensions either the bike manufacturer or the tire manufacturer must state that the tire/bike combination has a so called "clearance certification", i.e. either of the two simply means "it is safe riding this and that bike with this and that tires".

This topic here is an endless story full of discussions with of course different opinions. Some say it is still enough to have simply the right dimensions, some say you need this clearance certification".
My private opinion is that I only ride "released" tires for my bike because I do not want to risk to be fined or (what is even more worse) to lose my insurance coverage.