Somes manufacturer sale tires 275 40 18"
which normally should be 275 mm wide and the foot print very close.
But in fact some are at 260 with a foot print of 235.
far from what you expect.

Can we here tell what our experience is? helping us when purchasing new tires. I measured the stock

tHE GOOD YEAR EAGLE F1 are
260mm foot print for the 275
220mm foot print forthe 245

What are the BF good rich Kumho?

What I called foot print is the rubber in contact with the road.

 

Don't understand what you're asking - actual tread width vs. advertised?

How are you measuring actual?

 

Maybe reword your question, I can not understand what you are asking.

 

sorry guys first post has been modified with more details.
Let me know if it is still unclear.

 

I understand what you mean now. I have heard that many tires are different widths but rated the same. I really have no idea where you could get data about this. Good luck.

 

what should be good is that anyone measure what they curremntly have or can measure

 

I believe that tire width is measured from sidewall to sidewall and is not an indidcation of tread width - which is usually narrower. Ergo, two different tires with a 275 mm width can actually have different tread widths (footprint).

Section Width
A tire's section width (also called "cross section width") is the measurement of the tire's width from its inner sidewall to its outer sidewall (excluding any protective ribs, decorations or raised letters) at the widest point. This measurement is made without any load placed upon the tire and after the tire has been properly mounted on its industry assigned measuring rim and has been inflated and reset to its test pressure after 24 hours.

Because a tire's section width is influenced by the width of the rim upon which the tire is mounted, the correct industry assigned measuring rim width for the tire size being measured must be used.

The width of a tire mounted on a narrow rim would be "narrower" than if the same tire was mounted on a wide rim. NOTE: because the overall diameter of a steel belted radial is determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".

For example: a tire in the P205/60R15 size is measured on a 6.0" wide wheel and this size tire has an approved rim width range from 5.5" to 7.5" wide. The tire has a section width of 8.23" (209mm) when mounted on a 6.0" wide wheel. If that tire were mounted on all of the rims within its approved range, the tire's approximate section width would change as follows:

Difference from
Measuring Rim Rim
Width Approximate Tire
section width
0.5" narrower 5.5" 8.03"
Measuring Rim 6.0" 8.23"
0.5" wider 6.5" 8.43"
1.0" wider 7.0" 8.63"
1.5" wider 7.5" 8.93"

Because of the different wheel widths used in the above example, there is a 9/10" projected difference in tire section width when comparing a tire mounted on the narrowest rim to the widest rim within its range. This may affect fenderwell and frame clearances when selecting optional aftermarket wheel and tire packages

Tread Width
The tread width is the distance between the outer edge and the inner edge of the tread of a new tire. However today's radial tires often feature tread designs that incorporate rounded shoulders and there is no industry standard pertaining to "how much" of the rounded shoulders should be included in the tread width measurement. Because of this, it is difficult to accurately compare the tread width differences of one tire brand to another. Tread width measurements are best used when comparing the various tire sizes or lines manufactured by a single tire manufacturer. Several tire manufacturers have chosen not to publish tread width dimensions.

 

If you go to Tirerack.com and look up a specific brand of tire and look at its specs. It will give you tread width on some of the Tires Listed. Here is a link to get you started.

http://www.tirerack.com/tires/Spec.j...omCompare1=yes

 

Corvettefrance is exactly right in his first statment, however there are several variables that affect the actual footprint of the tire.
1 is rim width and 2 is tire pressure and 3 is actual load placed on the tire.
The widths published on the tirerack's website are in no way real world tire footprints.
The only way to measure real footprint is to roll the tire mounted on the car across something like a sheet of paper and measure the width of the mark left.
I have actully seen narrower rated tires leave wider footprints then the so called wider tires.
This is because of the rollup of the tire tread on the sides.
Rim width is probabably the most important factor in obtaining the desired footprint if it's to wide the tire lifts in the center, if it's to narrow the sides roll up, both will defeat the purpose of the tire selected.
Another factor is usage of the vehicle, if you like to road race then roll up is important, but if your drag racing you don't want roll up you want the flattest foorprint you can get and the longest.
Then there's the compound issues and etc etc
Bottom line is your tire selection should be done by someone with first hand knowledge of your driving habits and desired usage, not by the numbers on the sidwall. Their just a starting point!

 

I agree with your theoritical statement.
But in real life thing are different and I feel that some manufacturer may actually cheat.
The are selling you a 265 tire real dimension for a 285 (marqued on the tire) and therefore when you look at the price and you compare it to another 285 (which may be a real 285). The first (265 ) is cheaper.
On the wagon wheels that I used to go on the road track.
As I wear the tires pretty fast I already went to about 20 tires.
I always buy 275 or 280 650 18 that means 650 is the outside diameter of the tire. It equal to a 30 serie's tire.
Some are 25mm wider than other all are supposed to have the same specs except rubber quality.
And I now this is the same for street tires.
I bought a set of Wanli 205 40 17 for my son on ebay recently.
they are not true 205 if you install a BFgoodrich 205 on the same wheel it will be wider.
And I am here on these example talking only about the width of the tire (part not in contact with the road).
In addition some have a big radius and the rubber in contact with the road will have an additional 10 to 20 mm less.
At the End two identical tires (on specs) will have a huge differnce on the road.
And for us with 275 or 295 it is not as bad as in 205 where you compare 180 mm in contact to 140 mm it is a 30% difference

 

 

I would have to add all tires brands, are different in size, so do not good by the manufactuers demensions. Tape it or chalk it yourself. At the end day, is comes down to contact patch, tread width(minus the grooves), consistancy, wear rating, feedback, etc., etc. Track and street perfomance over time is the real world measure. Sorry, if that is a chitty answer, but it is really the truth.

 

Hoosiers are cheater tires.

my Mich PS 335s are 13.1 in wide the Hoosier 335s are 13.6 in wide AND the Mich PS has a flat side wall. the Hoosiers have a curved side wall so the Hoosier is more like 14" wide.

 

Hoosier are not cheater they give you more rubber for your money.
For me cheater are the one with narower tire vs what advertissed.

 

One is called tread width and the other item is called the contact patch.
There is a difference between the two, and varies from tire to tire, and is also affected by your rim width.
The contact patch sizes are all determined by using the optimum rimwidth for the specific tire size.