Hi
Life depends on use and storage, both can reduce life.
Rubber wears, when used and vulcanises (hardens and cracks) when exposed to UV or stored out of shape.
I would recomment a max of 4 years if you expose the bike to sun, based on UK sun, you know that orange thing hidden behind the rain clouds. Sooner if you you actually get any

Of course, no one rides in the sun

Or did i read all this adverts incorrectly, maybe they said never ridden in the rain?
Wear is easy to spot.
Try to ride some bends, we have plenty of these on our roads in the UK, to avoid the flat on the tyre.
I got around 8k on the front stock tyre, and replaced the rear after a puncture or two.
Now using PR4 tyres, got a great deal from the local Yamaha dealer on these.
i chose these due to daily riding, often in the wet and their ride/wear spec.
When storing, try to lift the wheel off the ground, or turn the wheels every few weeks to prevent a flat spot, make sure you top up the air too.
Tyre is the English spelling for American Tire, just in case anyone noticed.
David