Binding Brake Width
The short answer is that you don’t need to. Bring your unmounted skis to a local specialty ski shop with a strong reputation for service, tell them which binding you want, and they’ll take care of the brake width.
But, if you’re shopping online and need some guidance, here goes:
Brake width loosely matches up with the waist width of the ski. With Peak, waist widths are easy to figure because they’re also our model names. The Peak 88 is 88mm at the waist (underfoot), the 98 is 98mm at the waist and so on.
Most binding manufacturers will list a brake width range on their bindings. For example 85mm to 95mm. That clearly would be the best option for our Peak 88, but ski brakes are a bit fungible. That 95mm brake will almost certainly work just dandy on our Peak 98 too. It’s three millimeters we’re talking about and binding techs always tweak brakes to fit.
When in doubt, leave yourself some extra brake width, but don’t go crazy. Never buy a brake that’s more than 15mm wider than the waist of the ski. If your brakes are too wide, you risk hooking them together or catching them in your ski pants and suffering a silly crash.