also go direct to peter mays website where he explains is rationale on creating speed ratings. its a complex subject but you cant expect the ratings to always win as every race is a unique event and ran with hundreds of diferring scenarios.
the speed ratings are there as an additional tool to try and narrow the field and should in my opinion never be judged soley on the spped figure, peter may himself says you have to ensure the horse matches the particular conditions of each race.

Your first 30 days for just £1