tire sizes - what they mean

[arsenic]

ok, in a recent post involving someone using a 160/70 rear tire. It struck my that you guys need to know how tire sizes work. Just because the front is a 120/70, if the rear is a 160/70 that DOES NOT mean they are the same profile, quite different in fact. Let's use a 160/60ZR17 for an example (this is the same for EVERY tire size).
160 - the width of the tread in millimeters, in this case 160mm
60 - the ASPECT RATIO that means the sidewall height is 60% of 160mm or in this case 96mm.
Z - the speed rating
R17 - Rim size in inches, in this case 17" rim.
so that is how it works.

[Tmod]

Don't forget that a 160 from Metzeler will not be the same width or height as a 160 from Dunlop either. The best way to check tire sizes is measure them. The sidewall info is just a reference.

Tmod

[Trackerrrr]

The "R" actually stands for Radial also. A bias ply tire won't have the "R" in the size designation.

[etskatana]

there not exactly the same cause they have a certain % of diff they can play with.....

[arsenic]

this post was made simply so members can have an idea of what they mean. Just because the front is a 120/70. Making the rear a 160/70 DOSE NOT make them any better. I just wanted to let members know what the sizes mean.

[Cheriff]

so now how big of a tire can I fit on my Kat?

[JasonChen]

thanks for the info arsenic! could you give some examples how the aspect ratio affects handling?

[Kreylyn]

Taller sidewalls absorb more bumps and roughness, giving the feeling of a "smoother" ride. They also flex more on the curves, giving a less than secure feeling on the turns in performance aspects.

Shorter sidewalls generally means more "feeling" of the road... every bump. Less flex on the curves give better feeling on high speed turns.

Over generalization, but that is about the basics of it.

Krey

[arsenic]

Taller sidewalls absorb more bumps and roughness, giving the feeling of a "smoother" ride. They also flex more on the curves, giving a less than secure feeling on the turns in performance aspects.

Shorter sidewalls generally means more "feeling" of the road... every bump. Less flex on the curves give better feeling on high speed turns.

Over generalization, but that is about the basics of it.

Krey

what he said

[ATOMonkey]

Assuming the same wheel size and overall tire height, a tire with a lower aspect ration (wider same height same sidewall) will also tend to move more or squirm, since the tire isn't supported as well as it would be on a wider wheel. In a hard turn, the tire will actually roll over a little bit, and it feels like riding a bike with low air in the tires.

[forsaken]

well at least he didnt call me out by name specifically. only reason i was looking for a 70 was cause that is what was on it. ended up with a 160/60/17 anyway, but thanks for the info!!

[tone]

Would someone now like to explain the date code

[Kreylyn]

Would someone now like to explain the date code

Sure, if a guy pays for the entire dinner and movie, some kind of nookie is expected in return at the en...... oh, wait... Your not talking about THAT Date code....

The date of manufacture is indicated by the last group of digits in the DOT manufacture code on the sidewall of the tire. The number is often stamped in a recessed rectangle. The DOT code tells who manufactured the tire, where it was made and when. The last group of digits in the code is the date code that tells when the tire was made.

Before 2000, the date code had three digits. Since 2000, it has had four. The first two digits are the week of the year (01 = the first week of January). The third digit (for tires made before 2000) is the year (1 = 1991). For most tires made after 2000, the third and fourth digits are the year (04 = 2004).

Krey

[RussianMonk]

Putting the fattest tire is not always a good idea. I can think of at least 2 issues with this. One - You would need to make both front and rear tires wider to keep the handling right. Do you think the choppers with the giant rear tire and a skinny little one in front handle well? Nope. In many cases a skinnier tire will mean quicker response when turning. Racers will go to a skinner tire when they need to be able to turn quicker. Two - If you put on a fatter tire and the rim is still factory the tire will roll more side to side because of the fact that the sidewall is stretched to a thinner wheel. If you were to upgrade, you should upgrade both wheels and tires. Just my 2 cents...

[alpinestar]

how will a radial tire be different from a non radial tire ( like a metzeler ME55 ) ?