Tyre replacement best practice

[Ozone]

My M135 has developed a slow puncture in one of the rear tyres that have covered 8.5k miles, if it's not repairable is it best to get both the rears changed or will it run ok just replacing one? There is probably about 4k of tread left on the rears.

[Ozone]

Thanks. I'm going to my local indie who I trust and see what they say. Good point about the weather changing