Tire load ratings depend on pressure, and that load rating/tire pressure relationship does change depending on the tire size/brand/pr. The tire data sheet should be able to tell you what psi is required to support a particular load. The OEM pressure is setup to support a particular axle load...
I banged my knee up pretty good doing an autocross last week. Nothing major, but it was definitely bruised after 12 runs.
I found a great black Alcântara knee pad on eBay that fits perfect.
Suede Knee Cushion for Car Auto... https://www.amazon.com/dp/B07V1JKFG2?ref=ppx_pop_mob_ap_share