Tire change

[rubi]

Would it hurt to change one tire at a time? What if they had different treads??

[Tups]

Even though they say that tires should always be changed in pairs, one axle at the time, and better tires should be put on the rear axle, I guess there's nothing wrong in buying one tire at the time as long as you're not driving in snow or rain and, well, avoid any situation in which the tire's performance may play a great role. The worst case scenario in the latter one is that when you slam the brakes, the car will turn sideways because of difference in the frictional coefficient of the old and new tires.

[padauk_dust]

It is fine, just make sure they are the same size & type; and have a similar tread pattern.

[theholycow]

On your very old car, just make sure there's no large difference in measured circumference of the two tires on the drive axle. It should be good enough to measure diameter and see if it's within (I'm guessing) 5mm. On the drive axle, having too large a difference can probably damage the differential. On either axle, having significantly different sizes might cause uneven braking and handling.

A modern car with ABS and other such things would be more sensitive to small differences in size.

[rubi]

Turns out my very old car is doing okay except that the rear left tyre kinda melted on the road yesterday, so now I have no spare, I am gonna get the other one anyway. Thank you all.

[rubi]

Funny thing my car was more balanced with 2 different tires in the front, now I've got the matching tyre and moved the front left one to the rear, i guess i need to go check my balance. Not that big of a deal anyway. But I've learned important facts about tyres not that I didn't know them, but actually experiencing the difference is what teaches you.