I like the Losi Bolt-Ons. I run them on Proline 40 series rims with 23mm hexes.
They are taller then the proline 40 series tires, have great traction and seem to not be wearing much at all.
http://www.rcslot.com/pc-radio-contr.../LOSB7206.html
best price I have found on them so far.
I have pics of them on my revo if you need to see them.