I often receive emails from BMW owners asking me what I think the right tire for their car is, or if they even need new ones. Sometimes they even want to know why their friend has one brand while they have another. Since we car folk are often afraid to ask questions at the risk of looking silly, I thought I’d make a BMW tire guide to help.
There’s nothing new here, but man, some of those articles are so dry. I’ll try to make it easily digestible in my usual humorous tone.
We start with a trip to high school auto shop.
Does your BMW even need new tires?
I took auto shop in high school, and I’d call it one of the few genuinely helpful classes that carried over into the real world. Mr. Joe (who once put a Taurus SHO engine in a Pontiac Fiero as a class project!) introduced us to how tires work, why we can’t all drive around on slicks, and what a wear bar is.
Feel your tire (lovingly). In between the treads, you’ll see a small raised line. This is the wear bar. As a general rule, when the tread wears down to that bar, it’s time to replace them. I’d do it a little bit before that, so keep an eye on it as you drive your car.
Tire wear is gradual, like gaining weight. You don’t wake up one day, look in the mirror and see the Nutty Professor. It takes time, then suddenly you have that hot date planned and try to squeeze into those jeans. Same with tires. They are ok until poof, they are worn. Chick in with them often.
Do I need to buy BMW tire insurance?
Depends on a few things:
- Low profile performance tires? Yes. The dealer will almost never patch them, and if you do get a flat, the new tire is covered. A rear Michelin Pilot Sport tire for a G80 M3 is approaching $500. Pop a few of those and the warranty pays for itself. Plus, even if the tire is worn, they will usually give you a new one free of charge.
- All-season run flats? Meh. Even if the dealer won’t patch them, a tire shop will, and that’s almost always fine. Though not cheap by any means, it would take many more Continental radials to make up the price of a tire warranty.
How can I make my tires last longer?
Like any other part of your BMW, the more you abuse your tires, the quicker they will wear out. To extend their life:
- Rotate them every 10,000 miles
- Check your alignment
- Be aware of what a tread rating is, which is a guide to how long those tires will last. I’ll explain…
Why do I need to rotate my tires?
If your car has what’s called a “square” set up, it means all four wheels and tires are the same size. A 330i has a square set up, an M3 does not. And if you do have a square set up, you can rotate your tires, usually in an X pattern (rear left goes to front right). The fronts always wear out faster because they steer and thus rub against the road more. When you rotate them, you’ll even out the wear among all four wheels.
To help put high amounts of power down, M cars usually have larger wheels at the rear axle, so they cannot be rotated.
Do I need an alignment?
Dealers love to “recommend” this, but keep a few things in mind:
- Do you need to hold the steering wheel at an angle to go straight? You need an alignment.
- Are your tires worn a lot more on the inner edge vs the outer edge? You need an alignment.
- Have you done it recently? Within say, 15,000 miles? If not..yup.
Dealers can charge over $300 for one. They will usually provide you with a measurement chart that displays angles and degrees (we’ll get to that), and it should be all green. If it isn’t, have them explain why. If it’s slightly off, it’s usually okay since suspension components can bend. But nothing should be egregious.
Tread wear rating
This is a sort of pretend number that the government insists tire manufacturers add to the sidewall. It can be looked at as a guide for how quickly a particular tire will wear out. Remember that summer tires are softer with treads that are not as deep, so they will wear out faster. As an example of two typical BMW tires:
- Michelin Pilot Sport 4 – UTQG 300
- Pirelli Cinturato P7 All Season Run Flat – UTQG 500
The Pirellis will last longer, but are not as grippy. Think of this number like you might think of the EPA’s fuel economy numbers for your car – take them with a grain of salt.
Do I need to go to a BMW dealer to perform an alignment?
No. Any capable tire shop can do it. Tyspeed did mine when the M Performance Suspension was installed.
When you get an alignment, your car is put on a rack in front of a device that shoots out lasers (pew pew!). The mechanic then adjusts toe, camber and caster as needed (measured in degrees) according to what the rack is looking at.
Of the three available adjustments, toe is probably the one most responsible for tire wear, but all three can have a negative effect. This is a simplistic way of explaining it, but BMW suspensions are no different than any other make.
What do all those sidewall numbers mean anyway?
They look like some sort of ridiculous math equation, but they serve a purpose. Let’s decode the front tire on a G80 M3, which is 275/35ZR19 (100Y) XL AA A.
- 275 is the width in millimeters. This does not change, even if you order the base 18-inch wheels on the M3. Technically, the base wheels are the best for an M3 as they are the lightest.
- 35 is the “profile”, or aspect ratio. Anything 40 and below means low profile, or thinner sidewall. Sports cars generally have lower profile tires that reduce ride compliance but aid in sidewall flex.
- The Z and Y relate to the top speed of the tire. “Z” means the highest speed classification available, with Y specifically rated up to 186 miles per hour, well above the top speed limiter of the M3.
- That “100” before the Y is a weight classification, or how much load the tire can hold. 100 means a 1,764-pound maximum. Don’t worry, that’s per corner. The XL is simply branding, meaning this PS tire can hold more load. Hey, the G80 is a heavy car.
- Finally, the AA A. This is a “grip” and temperature” grade as rated by old our friends, the US Government. The grip rating on these tires is the best available, AA, while the temperature rating of A is also the best available. That test measures how well the tire can dissipate heat off its surface and still maintain grip. Remember, tires get hot from friction.
All my M3 friends have Michelin, and I have Pirellis. Why?
You did not win the tire lottery. Sorry. To keep everyone happy, BMW alternates the tire brands they put on cars each month at the factory. This keeps suppliers well-stocked, and consumers none-the-wiser, since the car is guaranteed to perform the same with whatever tire BMW selects. BMW advertises the M3 Competition’s 0-60 time as 3.8 seconds. It might be faster than that with Michelins, but it won’t be slower than that with Pirellis.
What’s the big deal about Michelins Pilot Sport tires anyway?
They are the best tire on the market, period. Search for reviews for a good basis of understanding, and take it from me because I’ve driven a ton of performance cars at this point. The best ones usually have them mounted.
The sportiest road legal tire that Michelin makes is called the “Cup 2”, and though you can put them on your car, expect a very short lifespan. Best reserved for track cars or ultra exotics like the Porsche 911 GT3.
Why do tire treads look so different?
The best-performing tire is a racing slick – it’s just rubber without any tread. And if we never drove around in water, this would be great, but we do. Hydroplaning doesn’t mean taking a shower on a 747.
Instead, we add treads which essentially “push” water away from the rubber and allow it to contact the road. The more grooves there are, the more effective it is at removing water, but the less dry grip is available. To put it another way, the more grooves there are, the less rubber is actually on the road.
So if you take a look at a set of performance tires, you’ll see big tread blocks and nice big contact patches, vs an all-season tire which has many smaller tread channels.
What’s a tire compound?
Tires are not just made of “rubber”, but a special mix of elements that react differently to heat. A good example is the “soft”, “medium” and “hard” tires of an F1 car.
This goes back to that tread wear rating. Performance tires are made of softer compounds that heat up and grip well, but wear out faster. They also turn into rocks in cold temperatures. Speaking of…
Do I need winter tires?
Yes, if you live in an area that you know will get cold. Cold for a summer tire means anything ambient below say, 45 degrees.
Maybe, if you experienced what I did in New Jersey this past winter – we had one snow event that totaled 2 inches.
Use your judgement. If you need to drive your car no matter what, put snow tires on just in case.
I can tell you that when mounting them on the X3 M40i, they make the car worse. They produce much more road noise, deaden the steering (well, deaden in more), and make the car more eager to lean over in turns. But it’s a safety compromise.
Are run flat tires bad?
Not really – they have gotten much better over the years. Run flat tires used to be accused of providing a rougher, noisier ride without much benefit. And having a low-profile version mounted on my F30s, I can tell you that any little pothole caused a bubble in the sidewall.
But if your BMW came with them from the factory today, I see them as a great way to not need a spare tire taking up room in your trunk. I’ve driven on them punctured, and they delivered me safely to the tire shop.
M cars do not come with run flat tires because they do not come in the “max-performance” variety. Instead, BMW used to give you the M mobility kit, which is a tire inflation device and a can of Fix-a-Flat. It sucks. Call a tow.
Do tires “expire”?
Yes, they have a shelf life, even if you don’t drive the car they are mounted on. Look for cracks in the sidewall and tread as a visual clue, but even if you don’t see any, don’t assume it’s safe to drive the car. They lose their ability to flex and bend over time.
I can think of no better example than Paul Walker. The Carrera GT he was riding in was on tires that were over nine years old.
Does all-wheel drive make a difference for tire wear?
Not really. You can’t generate much tire slip in an all-wheel drive car, which is why the M3 and M5 allow you to turn it off. Remember that all-wheel drive helps you go, but not stop or turn (unless you’ve decided to keep your foot in the throttle as you turn, but that’s racing talk).
Do front-wheel drive cars wear out tires differently?
Yes. On a car like a VW Golf that is strictly pulled by the front wheels, they are responsible for both steering direction and applying power. It’s very important to rotate them because the fronts are very busy.
BMWs work a little differently – even a 2 Series Gran Coupe has all-wheel drive that always sends at least some power to the rear. However, cars like the 2 Gran Coupe and X1 favor the front wheels, and they may wear faster than you anticipate if you like to stomp on the gas and break traction often.
So, like, are tires really that important?
I will leave you with this – they are the most important part on your car. It’s the only part that touches the ground.
If you have even a reasonably sporty car and you do not have summer rubber on it, consider that as your first upgrade. It makes a much bigger difference that a lower suspension or reducing weight. Everything will improve, from steering feel to stopping distance.
It’s also the one part you don’t want to cheap out on. Here’s a tip – if you’re looking for a used BMW and you see a cheap tire brand mounted on there, walk away. If they didn’t care about tires, they didn’t care about anything else.
So the next time you see a BMW with bald tires, send them this article, and tell them to get a grip ;-).
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