I've really found the speed I was looking for in my Powell SPF "Racing Stripe" wheels on concrete. Although, they tend to slip a bit on the park, I'm still able to hold my control. Now that the weather is changing and the indoor park is covered in Skate-lite or masonite, I'm thinking my SPF wheels will be too slick. Any recomendation on a set of "indoor" wheels? Any help would be great, Thanks!