Hardwood,
(I am in Stockholm/Sweden and had a 2020 Mercane Widewheel Pro (WWP) for two years. Also decently experienced MC rider for 20+ years.)
If this is for your 15yo kid, there is an important/critical factor to consider depending on your location’s weather.
-> On a wet asphalt/tarmac, typical after rain, the WWP is a seriously dangerous scooter to ride due to its hard-compound ultra-wide flat tires.
It has zero grip.
Similar to driving a race car on slick tires under the rain.
HTH.
E.