Rollerski wheels with many miles can become unevenly worn and not as smooth due to smaller diameter. Many variables affect how long the rollerski wheels will last ranging from skier weight, technique, aggressiveness, amount of plowing to slow down, pavement conditions, temperature, etc. We suggest replacing them once they are worn down to about 90 mm. Generally our speed 2 and 3 wheels can be expected to last 1,200+ miles. Our speed 1 is a multi ply construction with a protective ply, so much shorter life. Most people shouldn't be getting the faster speed 1's anyway. 

We sell 100x24 and 105x24 mm rollerski wheels in both built and unbuilt format. We normally build our wheels with 6 mm shoulder bearing spacers, but if you need 8 mm floating bearing spacers for V2 or Fischer roller skis, just let us know and we'll build them to that specification. Our wheels will fit many skate rollerskis made by other brands even. Some brands use really long bearing spacers that extend out beyond the side of the bearings that insert into the wheel spacers like Elpex F1's, but you're fine to reuse those wheel spacers as the smaller inner diameter still centers them on the wheel and axle. 

4 built 100 mm wheels are just $80.

4 built 105 mm wheels are just $100.

The wheel on top below is a customer's heavily worn Elpex F1 wheel that was past due for replacement: