Thanks for adding these, but please bear in mind that OpenStreetMap's default units are metric, so a maxspeed without a unit is in kilometres per hour. Imperial units need to be specified, e.g. 30 mph, 12'6", etc.

See:
https://wiki.openstreetmap.org/wiki/Key:maxspeed
https://wiki.openstreetmap.org/wiki/Key:maxspeed:type#United_Kingdom

I've fixed this in
https://www.openstreetmap.org/changeset/169662189