[Pete_vB]

The recommended rim for that tire per Michelin is 10", so you're using the rim the tire was designed for. I can imagine it's a stiff sidewall and not easy to mount, but the issue it with the installer, not the rim or tire.

I'll also mention that I personally wouldn't use that tire, for two reasons:

First, it was developed for the ZR1 as a front tire. Tires that are designed to be fronts have different construction (optimized for braking, etc) than tires designed to be rears (optimized for putting power down, etc). Generic tires are usually in the middle and can be used in either place, but the ZR1 will have front tires that don't work as well when used in the rear, which can lead to funny handling.

Second, the stiffer sidewall of a run-flat doesn't really play nice when mixed with a non run-flat. Tire response will be quite a bit faster with the stiff sidewall in the rear assuming you use a non run-flat in the front. This is why the tire rack says "NOTE: Pilot Sport Cup ZP run-flat tires cannot be mixed with non-run-flat Pilot Sport Cup". You might also need to adjust camber settings as the run-flat rolls over less than the non run-flat.

Might not be too bad, but if the car handles funny especially on turn-in keep in mind that the tires could be the issue.