The load rating is in the side wall, taller side wall will flex and when the tyre is pressurised ie from bouncing it'll push the sides outwards and force them into the rim more plus the tyre can (to a degree) roll sideways when cornering.
With very low side walls they are so rigid there's not much give so you have to rely on inflated pressure to keep them on and since this is present you get severe corner scrub which fooks them up
You see this when you are installing the tyre on the rim it's ni on impossible
And don't get me started on the bmw nuts who install stretched tyres into rims like 5j tyre onto 10j rim
Look at your weight plate and post the axle limits up here and we'll see what you can get away with if possible
(Ps. The above is my opinion)
56 350 2.2 130ps mk7 with 2 side doors
65 290 2.2 125ps custom with 2 side doors
07 350 170ps
Ids v86 licence + v86.04 update + xprog
hereIds map
here