I would be more comfortable finding a tire with a speed rating that exceeds the top speed I would be riding, versus the one it originally came with.
A strange thing on my Honda Helix is the Bridgestone Molas ML17 tires that came on it, originally, had a J rating for 62 mph. The scooter will cruise at 70 mph all day long. Weird, but for most people that is still their tire of choice.
I chose tires with a higher speed rating but those are no longer available so when it's time for replacements I may go with the old tried and true Molas, with 62 mph speed rating.
Good luck with whatever you decide to do.