I have just bought a Volvo S80 with nitrogen filled tires. Does nitrogen give a harsher ride?

No. The harshness of the ride in this case would come from the tire pressure among other things (springs, struts, tires, etc). Nitrogen in tires is used primarily to reduce maintainence (the need to check tire pressure often and refill with air) supposedly because nitrogen molecules are larger and less likely to leak through any "pores" of the tire. As nitrogen is also less likely to expand than regular air, most tire shops when using nitrogen, tend to fill more than the recommended specification because there will be no air expansion and no blowout (that may occur when tire is overfilled with regular air), hence the harshness of the ride.

Breath in.

You just took in 75% nitrogen.

To answer your question, it makes no effing difference. Air is air, no matter what the ratio of oxygen to nitrogen is. If you had not slept through high school science you would already know that.

Many garages say they inflate with nitrogen just to boost price, normal air is OK. Nitrogen for aircraft. I don't think you will notice any difference in the car. Does your manual mention it?!

If there's too much pressure in the tires. You don't need nitrogen unless you're doing over 100 mph continuously racing.

Standard compressed air is nearly 80% nitrogen. More importantly, whether you are running pure nitro or standard compressed air your ride comfort is not compromised or altered one way or the other. Whichever you are using does not factor into your ride comfort, only the quality of the tire does.

Air is 78% nitrogen.

The extra 22% will make zero noticible difference in daily driving.

No.

It is supposed to reduce damage from oxygen and most ure as it is dried and as a larger molicule leaks less

You need to go to a tire dealer for top ups with nitrogen.

It us useful in aircraft tyres and a bit of a debate in racing tyres. In normal cars the cost outweighs the benefits.

Nitrogen just doesn't expand as much as air when the tires get warm, evens out tire wear.

No. You wouldn't be able to tell the difference between pure N and 78% N (the air around you) by how a car rides when the tires are filled with either.

In THEORY Nitrogen gives a more BALANCED ride with LOWER tire temperatures as NITROGEN keeps cooler longest! BYE NOW!