when Should I change my OEM Potenza tires?

[WeeYari]

I don't know what it is like living in Egypts' environmental conditions. I would suspect that if you are not wearing the tires down within a reasonable timeframe, then one would have to monitor age of tire as well. Rubber compounds harden over time, hence becoming unsafe even if there is plenty of tread life left.

[yarswiss]

I changed my Potenzas after only 30,000 miles as they had become very slippery and quite dangerous when wet. This was even with 20,000 miles of babying the car and rotation every 5000 miles. I found getting new tires to be the best thing I could have done as it was a drastic change in both handling and ride quality. The Potenzas are also quite expensive for what you get. You could easliy find much better tyres for 2/3 the price.

[MUSKOKA800]

Originally Posted by WeeYari

I don't know what it is like living in Egypts' environmental conditions. I would suspect that if you are not wearing the tires down within a reasonable timeframe, then one would have to monitor age of tire as well. Rubber compounds harden over time, hence becoming unsafe even if there is plenty of tread life left.

5 years is the general guideline for replacing tires whether worn-out or not. As WeeYari has stated the rubber degrades over time and performance and reliability is compromised.
That said, I can't imagine the cheesy OEM tires on my Yaris being roadworthy in five years. These Goodyear LS's offer scant dry traction now at only 2 years of age even with >50% tread depth remaining. Oddly they work okay in the wet while at the same time are terrifying on the slightest bit of snow. All season NOT. Monsoon season maybe.
I'll be shopping for some sticky sneakers this year once the winter boots get packed away.