Let's say you don't drive your car much, only short distance and after 6 years the threads on the tyres are still 4mm. Is there age limit for tyres? Can I use it for another year?

not mistaken, max age 10 years, but recommend to change every 5 year coz the tyre will harden by then

Yes, there is a age limit.
10 years.

I didn't know it was 10 years. I heard people saying it's 5 years and I wanted to stretch 2 more years.

Can but just observe if the rubber condition still ok, not too hardened and not too much cracks.

10 years lifespan from manufacturing date. but malaysia weather so hot. my car tyre 5 years already hardened even tho not yet achieve mileage for some of my car.

I would have kept the tyres until 10 years for my backup car if it didn't start showing cracks under the sun

I dont think anybody use till 8-10 yrs lo
Maybe max 5-6yrs
But depends on ur tyre condition and driving style la, if u slow driving type 7 yrs still ok
But of course old tyres feel hardened like rock sometimes

just changed my old tyres (year 2015) last months... low mileage, 13k done on that tyres for 6 years

You may, but at a greater risk with each passing month. You can deflate it partially and inflate back to check for noticeable cracks due to hardening (if any). If that's what you need to do, then be wary of driving erratically, aggressive maneuvers, pay attention to pot holes (as we normally do in Malaysia) and the likes. Especially so if you have family with you.

I personally would not use more than 5 years, but everyone has different priorities. Just drive safe.

I keep my spare tyres up to 10 years, before replacing them or throwing them away.

brand new rite. u may use it during tyre rotate.

If same size can, but now more & more is smaller emergency type so no choice..

yalo. lagi new trend is no spare d. gift a repair kit
or runflat straight

I can't use it on normal conditions. My spare tyres on all my cars are the smaller type ones. Haha

Until I felt it very bouncy.