I used to visit people in Bucks and I can assure you that your roads are a great deal better than those down here in "pot hole county" in the Southwest. With total road mileages near if not the greatest length of any county in England (the 3 Ridings of Yorkshire might be the exception) and with the smallest allocation of budget due to legal requirement associated with care etc we have plenty hills and very many potholes.
We need some of your road maintenance allocation re directing down here.
The size of the wheel is not irrelevant.
Aa we all know you can’t fit the 4 pot or 2 pot Calipers under a 15” wheel. So if wishing to retain the 15” wheel (or at least have that option available) the the option of 280 discs is the way to go.
My point about leverage was this.
For the same caliper with the same pad and same pedal pressure the clamping force is the same. At a greater radius the applied torque must surely be greater. But as expressed by MGB281 there are other factors such as tip speed of the brake rotor. There are numerous “papers” on this subject.
Personally I just want something that is a bit better than standard that works for both me and as Cobber would say “my glamorous assistant”.
For touring the 15” wheel with a deeper section tyre will hopefully give a slightly more comfortable ride.
I didn't understand that you were talking about wheel fitments, I thought you were referencing wheel diameter with regards to their effect on braking. In your reply you state about the greater torque due to the greater leverage, that is exactly what I said with the 20% increase in braking effort between 240 and 280mm discs, if you wonder why it is 20% and not the 16.66% that the discs increase in diameter it is due to the fact you have to measure at half brake pad height
