A roundup of tire tips for choosing your next set — and on making them last longer

Dear Car Talk:

I’m a 70-year-old woman who drives a 2016 BMW 228i xdrive coupe. The current tires are Continental run flats that came with the car, which — at 28,000 miles — the front tires are bald. The rears still have some tread, but I need to replace the tires and have a few questions:

• How do I determine if I have “staggered” tires? I assume not, but the guy at the tire store asked.

• I’ve always liked Michelins, and they have both Y-rated tires and V-rated tires. Which do I need?

• Do you still recommend rotating the tires? Some places will do it for free if I go back there regularly. Only front to back, or cross them in an X pattern?

Sorry for so many questions! — Caren

You are correct that you need four new tires. You have an all-wheel-drive car, and to avoid doing harm to your center differential, you need four tires that are all the same diameter.

Worn-out tires will have a smaller diameter. So you now need four new ones.

How do you know if you have staggered tires? Look at the tire sidewall for the measurements. The tire’s width is shown in millimeters, like “195” or “225,” and you’ll find it inside a string that looks something like “P225/55R18.”

If your rear tires are wider than the front tires, your tires are considered staggered, and you’ll need to buy two wider tires for the rear wheels. But you don’t have staggered tires (we looked it up) on your model 228i.

The letter (Y, V, etc.) is the tire’s speed rating. And unless you’re a closet Lightning Mcqueen, you don’t need the pricier Y- or Vrated tires. Y-rated tires are good up to speeds of 186 mph and V-rated tires are good up to 149 mph.

An H-rated tire (130 mph) will be more than adequate for your purposes.

And Michelin makes very good tires, in our opinion. But you can buy anything that’s the same size as the tires you’re replacing.

Do a little research, though. Check Consumer Reports or Tire Rack and find a highly rated tire rather than just accepting whatever the local tire shop has lying around.

Once you get your new tires, we do recommend rotating them.

Your current front tires wore out faster than your rear tires because front tires do most of the braking and all of the steering. But because you have all-wheel drive, you now have to buy four new tires even though only two of your tires are completely shot.

If you rotate your next set back to front every 5,000 or 7,500 miles, they’ll wear out more evenly, and the whole set will last a little longer.

And as long as they’re not staggered, you can move them front to back or crisscross them.