Does anyone know a guide for motorcycle tyre pressures please?
the pressure rating on a tire is the MAXIMUM pressure it will take without blowing, not the optimum handling pressure, your motorcycle should list the correct pressure depending on weight either under the seat or on the swing arm. The correct pressure should also be listed in your owners manual. Don’t go by the tire, go by the bike, one size tire can fit several different motorcycles, only the manufacturer knows the best pressure for each application.
read the tire it is on it fill it to the max pressure it is rated for it is rated to carry the most weight at the rated pressure different brands of tires have different pressures with a passenger you are close to the max carrying capacity you need the tire to match the rating on the frame is for the original brand type and size of tires
