Welcome to the forum!
My Contis lasted 43,000km and might have gotten me to 45,000km but with one punctured and the rest looking sad I decided to replace them. BF Goodrich ATs are on, have done 24,000km with them so far and they're still looking really good.
I'd suggest that you stay with the standard tyre size (255/70R16) as well. Increasing the tyre size might make your speedo APPEAR to be more accurate, but it's only the needle you're influencing - the ECU knows how fast you are actually going (on standard tyre sizes) and your odometer is quite accurate. Changing tyre size will change that.
Going up in tyre size will also reduce your fuel economy. I'm using at least one more litre per hundred km with the 2% larger tyres I have now (265/70R16). If I'd gone to 265/75R16s I'm sure it'd be worse again.
If that's not the worst - your car will also "feel" slower. The gearbox and diff ratios were chosen with the 255/70R16 tyres in mind.