Losi tires have a slightly wider bead than Proline. You will find it easier to mount them to Proline/Associated rims if you trim the bead 1-2mm narrower so they fit in the rims better.
"I have no idea what you're talking about, so here's a bunny with a pancake on it's head."
In mind and body, we're all heading towards old age. It is slower to go by bike.