I had 15 years in the tyre trade-
ultimately owning a shop selling to car/van users, we would welcome bikers with punctures as they were self-sufficient, and up the creek without a paddle.
Now I am a biker!

re- speed ratings and legality.
As far as I'm concerned it is ok to fit tyres to your vehicle of lesser rating than OE(original equipment).Winter tyres are not at the same rating as "summer tyres" for example.
It's all down to the "construction and use regulations".
Basically if you're knicked at 135mph on H rated tyres you're knicked twice.
H=130mph T=119mph
Speed symbol - Maximum kmh mph
N 140 87
P 150 93
Q 160 99
R 170 106
S 180 112
T 190 118
H 210 130
V 240 149
W 270 168
Y 300 186
(for your info -car stuff really);
if your car is fitted with W-rated tyres, and you tow a trailer, then in the UK that trailer may have T-rated tyres (if applicable), but in France your trailer tyres' rating should match that of the tow vehicle.( change tow vehicle tyres!-Hi speed caravan tyres?-I don't think so)
Re ; puncture sealant,
The Police don't use it. If an object penetrates the tread and protrudes inside it could damage the cords from the inside leading to a blow-out.
They ,however have a radio and recovery trucks ,get paid to wait.
hope this helps
