When is a 160 not a 160?

[Molly]

When it's a 140...

Bought an old stock tyre from my local H-D dealer. It's a Dunlop Touring K177 and stamped as 160 / 80 / 16 / 75H. I've measured it and it's no more than 140 at its widest point (my stock tyre is a 130 - 2001 RK by the way). There seems to be enough room to squeeze it in so unless it suddenly manages to expand 20mm I remain confused...

Go on, tell me I can't use it... Rain on my $50 tyre bargain parade why don'tcha ;-)

[CraigArizona85248]

If you measured it at 140mm uninflated, then it might be 160mm once you air it up.

-Craig

[Upswept]

The 160 is 160mm measured tread width.  It is measured from one end of the tread width and follows the round contour of the tread, not a flat measurement from above.

[Molly]

I see. I guess that explains it.

All these years I didn't know that. I think most people assume it's just the width.

Cheers.

Molly.

[Deye76]

When it's a metzler made in Brazil.

[Molly]

Ha ha. Sounds like the voice of bitter experience...

[RK103]

Tire Size & Service Description (e.g. P185/70R13 89T):
   P   Tires with a P are using a P-Metric designation, which is the American market sizing standard started in 1976. All P-Metric tires are engineered to standards of T&RA (Tire and Rim Association). The "P" stands for "Passenger" vehicle. If there is no "P", the tire is engineered to ETRTO (European Tire and Rim Technical Organization) standards and is considered a metric tire. Standards by ETRTO and T&RA have evolved together, and are virtually interchangable. 
185   The first number on the tire size is the cross-section width. This value is the width of the tire from side-wall to side-wall as measured in millimeters.  
/70   The two digit number just to the right of the slash (/) is what is referred to as the "aspect ratio". Not a 'specific length', this value describes the distance between the bead of the tire to the tread as compared to the cross-section width. This is viewed as a percentage value. (e.g. P185/70R13 has an aspect ratio of  70% of 185mm....or 129.5mm.). Lower apect ratios confer a stiffer ride and increased control than a similar sized tire with a larger aspect ratio. But larger aspect ratios tend to be more absorbant and add to a smooth road ride. 
R    This letter indicates the type of ply construction in the tire's casing or carcass. "R" means radial. "D" means diagonal, referring to bias tires. "B" means belted for belted-bias tires. Never mix radial tires with any other constru ction on a car. 
13   Rim Diameter. It is the diameter of the bead seat in the rim. Most tires are built to inch standards for rim diameters. However, some tires are built to millimetric rim dimensions. Always match the tire's rim diameter to the wheel rim diameter. 
89   Load capacity. Refer to the load index chart of a tire guide to find the maximum load carrying capacity of the tire. 
T  Speed Rating. This designation should be compared to the Speed Rating Chart to view the recommended maximum speed for this tire. 
Approved Rim (measured):
This is the suggested rim width range that the specific tire should be mounted to. The number in parenthesis is the rim used to obtain other values in this chart, such as over-all width.

Overall diameter:
The diameter of an unloaded, inflated tire measured from the crown on one side to the crown on the opposite side. The free radius equals one-half the overall diameter. Sometimes called the outside diameter.

Overall Width:
This is the widest measurement of the tire from side-wall to side-wall. The width of tire buldge at full inflation.

Tread Width:
This is the width of tread, side to side, in inches that actually contacts the road suraface when tire has full inflation.


 
   

[Deye76]

Ha ha. Sounds like the voice of bitter experience...

Yea, no secret I got a case of the red arse for metz.  And a tech, Jeff Johnstone, didn't help matters. But then I'm not a famous chopper builder, with a tv show either.

[charley992002]

Well guys stand by for the next Dunlops you buy.  We got in some new Dunlops and the label looked different and the word tire was spelled tyre.  So I also notice the front 130/90-16 tires looked narrower as well, so upon further investigation, they are made in Indonesia.  At least the other Dunlops were made in Japan, hey our carbs, shocks, forks etc on our Harleys are Japanese.  But China, Taiwan, Indonesia etc just galls the hell out of me.

Rant mode off.