Not really classic territory but perhaps the knowledgable peeps on here might be able to shed some light on this... This is about theoretical maximum speeds and 'speed' ratings for tyres ( R, HR, ZR, etc for radials & FKW for crossplies). A few years back there was a seemingly unresolved debate about fitting agricultural dumper tyres to Range Rovers & Landies. The tyres were (typically) marked with "Max Speed 30Mph" The great debate was about wether this meant they could only be fitted to a vehicle not capable of exceding 30 Mph, OR, a vehicle capable of more than
30 Mph should not exceed 30Mph if fitted with such tyres. Does the 'speed' rating of the tyres set the maximum road speed? Or does the vehicle's theoretical maximum speed determine the tyre speed rating? In this case we are talking about 750X16 crossply 'dumper' tyres fitted to a Discovery. Obviously we are talking about very limited road use but would it be legal to use them on the public highway if the tyre's rated speed was not exceeded? Hope you can make sense of this...Simon H