I've said this before, the figure quoted on the side of the tyre is the MAXIMUM pressure, not the working pressure.
The type of tyre has very little bearing on the pressure, but the axle weights of the vehicle and loading are all important. The work to which the tyre will be subjected is also important.
None of this crap about the engine being at the front so the greater pressure should be in the front, and please no more very dangerous advice that the tyre should be inflated to the maximum given pressure shown on the side of the tyre.
As an example; the figure quoted on my current set of tyres is 50 psi, which according to Thor is the pressure I should run them at, but I inflate them to the book listing of front 30psi and rear 38psi. They aren't the tyres which the factory originally fitted, they're probably the third set of Goodyear Wranglers.
The vehicle manufacturer has done all the calculations and measurements so that they can make a recommendation regarding the correct tyre pressures for tyres fitted to their vehicles.
The only tests and measurements which the tyre manufacturers can make refer to the maximum safe working pressure, the absolute maximum pressure, the maximum speed and the maximum loading. They do not manufacture tyres for a particular vehicle nor do they quote the working criteria for any particular vehicle. They only quote for their own products.
I have never seen a warning in any owner's handbook stating that the tyre pressures shown are only for the original tyres fitted in the factory and good for no more than 20,000 miles or the first 2 years of a vehicle's life.
Think about it!