The "load index" is something that many tire shops will even get it wrong (or not bother to specify it). It refers to the maximum weight the tire can support (http://www.hogantire.com/tcloadindex.htm). I think they should be matched, or exceeded.

I bought my 98 V70 XC used from a dealer (50k miles ago), who had installed Michelin MX4 205/65 R15 92S. The car's recommended tire pressure (per the placard inside the gas filler door is:

Recommended 36 front / 41 rear
"Optional: 34 front / 32 rear

When I look at the max pressure on the sidewall of the tire, it is something like 35psi (I can't recall the actual #, but it is definitely lower than Volvo's "recommended" tire pressure for both front and rear). I therefore use the "optional" tire pressures on the car.

When I started looking for new tires (the Michelin's are ready to give up the ghost), I want to make sure that I get the correct "load index", and also make sure that the new tires can handle pressures up to at least 41psi, so I can try to inflate the tires to the "recommended" pressures.

When I spoke to the dealer, they said that they never look at the load index when they install new tires for a customer, and they just fill to 32psi all around. Even when I spoke with Michelin customer service, it was hard for them to let me know the max tire pressure (generally, the higher the load index for a certain tire size, the higher the resulting max pressure).

Good luck