Help! Tread Width Confusion

[Bobombo]

I'm running performance pack wheels right now but I'm planning to go square setup.

I deciding on between 285/35/19 and 295/35/19.

I'm looking on tirerack at the tread width section (I'm assuming the contact between tire's and road's surfaces).

My 275/40/19 has 10.1 tread width, 285 has 10.0 and 295 has 9.8.

So what's the point going to 285 or even the 295?

I'm a little confuse so hopefully someone can explain it. Thanks.

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[MButler51]

I'm running performance pack wheels right now but I'm planning to go square setup.

I deciding on between 285/35/19 and 295/35/19.

I'm looking on tirerack at the tread width section (I'm assuming the contact between tire's and road's surfaces).

My 275/40/19 has 10.1 tread width, 285 has 10.0 and 295 has 9.8.

So what's the point going to 285 or even the 295?

I'm a little confuse so hopefully someone can explain it. Thanks.

Well, the 275, 285, or 295 number is the tire’s SECTION width (the measurement from the widest point of the tire’s sidewall to the opposite sidewall, straight thru the tire) expressed in millimeters. So that is always what it is, BUT tread width can vary a little between manufacturers. I’ve been in the tire business a very long time, and I see some 295s, say, whose tread is almost as wide as the section width, and others whose tread width is slightly narrower. Are you comparing the same brand/model of tire across these sizes? If so it seems odd to me what you’re saying. If you were looking at different brands or models of tires, I can see it.

While I’m here, I might as well talk about the aspect ratio (the “profile”) of tires - the 40 or 35 or 50 or whatever, within the size. That number is the sidewall height (rim to tread) expressed as a percentage of the section width of the tire, so on a 30 aspect ratio tire, the sidewall will only be 30% as tall as the tire is wide. A 50 series aspect ratio will be 50% as tall as it is wide, therefore the lower the aspect ratio, the shorter the tire’s sidewall is, or, if you will, the lower profile the tire is.

Still, a 285/30 will always be 285 mm wide (sidewall to sidewall), and a 285/50 will also be 285 mm wide, but will be a taller diameter tire, Tread width will be close, but doesn’t have to be 285 mm. Usually won’t be wider that 285, but will usually be a little narrower (and is expressed in inches, not millimeters). The tire business is crazy - mixing metrics and inches all the time.

 

[Bobombo]

Well, the 275, 285, or 295 number is the tire’s SECTION width (the measurement from the widest point of the tire’s sidewall to the opposite sidewall, straight thru the tire) expressed in millimeters. So that is always what it is, BUT tread width can vary a little between manufacturers. I’ve been in the tire business a very long time, and I see some 295s, say, whose tread is almost as wide as the section width, and others whose tread width is slightly narrower. Are you comparing the same brand/model of tire across these sizes? If so it seems odd to me what you’re saying. If you were looking at different brands or models of tires, I can see it.

While I’m here, I might as well talk about the aspect ratio (the “profile”) of tires - the 40 or 35 or 50 or whatever, within the size. That number is the sidewall height (rim to tread) expressed as a percentage of the section width of the tire, so on a 30 aspect ratio tire, the sidewall will only be 30% as tall as the tire is wide. A 50 series aspect ratio will be 50% as tall as it is wide, therefore the lower the aspect ratio, the shorter the tire’s sidewall is, or, if you will, the lower profile the tire is.

Still, a 285/30 will always be 285 mm wide (sidewall to sidewall), and a 285/50 will also be 285 mm wide, but will be a taller diameter tire, Tread width will be close, but doesn’t have to be 285 mm. Usually won’t be wider that 285, but will usually be a little narrower (and is expressed in inches, not millimeters). The tire business is crazy - mixing metrics and inches all the time.

Yes I'm looking at the same brand Michelin PS4S. The section width gets bigger with bigger tire as expected but the tread width is what I'm confused about. It should get bigger too. Did tire rack got the number wrong somehow?

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[ModularKid21]

Yes I'm looking at the same brand Michelin PS4S. The section width gets bigger with bigger tire as expected but the tread width is what I'm confused about. It should get bigger too. Did tire rack got the number wrong somehow?

.

Unfortunately, that isn’t always the case. It’s possible that the numbers are incorrect but I doubt it as Tire Rack measures the tires (or so I’ve been told) The last option says “MO1 Mercedes” indicating that the tire is made to spec for Mercedes so it’s not unusual for the tread width to be larger/smaller than the same tire that’s not a “spec” tire. Another example would be the MPSS. I was in the market for 295’s as well and found that there are three different 295/35/19 MPSS tires. There’s the plain Jane non spec one which has a tread width of 10”, an MO Mercedes spec tire with a tread width of 10.3”, and a Star BMW spec tire with a tread width of 10.4”. All of them list a section width of 11.9” though

 

[NightmareMoon]

Unfortunately, that isn’t always the case. It’s possible that the numbers are incorrect but I doubt it as Tire Rack measures the tires (or so I’ve been told) The last option says “MO1 Mercedes” indicating that the tire is made to spec for Mercedes so it’s not unusual for the tread width to be larger/smaller than the same tire that’s not a “spec” tire. Another example would be the MPSS. I was in the market for 295’s as well and found that there are three different 295/35/19 MPSS tires. There’s the plain Jane non spec one which has a tread width of 10”, an MO Mercedes spec tire with a tread width of 10.3”, and a Star BMW spec tire with a tread width of 10.4”. All of them list a section width of 11.9” though

Definitely odd that those “larger” sizes are smaller, but with the Mercedes spec tire its not that unusual for it to be a bit off the others.

It is what it is. Most of the time larger sizes will be larger. Good to check the actual specs before you buy.

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