Originally Posted by masi61

Which rims do you have the 28’s mounted on? I haven’t made actual measurements with wider tubeless type modern rims But I’m thinking you might eke out a bit more width with something with more internal width like a HED Belgium +, a Pacenti Brevet or a Velocity Quill. My theory is that a 28 would fit more like a low profile car tire and possibly ride a few mm lower.

The older standard Mavic Open Pro type aluminum clincher rims are like 14mm internal width which leads to the “lightbulb” tire profile with certain wider clincher tires.

It appears from the photos that you have adequate side clearance for a bit more tire width, it is the height under the brake caliper that is the limiting factor.