Kuba,
The load rating of 85 equates to a max carrying weight per tyre of 515 kg, with 91 equating to 615 kg per tyre. So unless your car weighs over 2000 kg, the tyres ore OK with regards to load rating.
The below link shows a load index table showing the relevant numbers:
https://www.bobjane.com.au/info/load-index-speed-symbol/