are the a5 alumilite front rims good for mx racing? the site says they have a rolled lip but whats the differece between these and the ultimate rolled lip fronts?

The A5 are a lighweight wheel which has taken the place of the .125 & .160 wheels. They have been tested to be as durable as the .160 wheel but lighter. I'd say if ultimate durability is the goal then stick with he Ultimates which have proven to the strongest wheels. If weight is an issue and you aren't killer on the wheels at the price difference may make it worthwhile to try a pair.

Hope that helps