Q: What is the circumference of my tire?

<p>In order to accurately program a <strong>bicycle computer</strong> , it is generally necessary to enter the exact tire circumference. The tire circumference varies depending on the rim, the inflation pressure and the load on the tire. For these reasons, it is not possible to list an exact tire circumference. <img src="https://storage.crisp.chat/users/helpdesk/website/cff55f369977f800/dimensions-chart-cicumferences_1n2kn2o.png" alt="Approximate tire circumferences" /> In order to accurately program a bicycle computer, we recommend a simple rolling test with the rider on the bicycle where a mark is made on the tire, and the distance between it's contact point with the ground is measured across one full revolution.</p>

Question 1

What is the circumference of my tire?

Accepted Answer

In order to accurately program a bicycle computer , it is generally necessary to enter the exact tire circumference. The tire circumference varies depending on the rim, the inflation pressure and the load on the tire. For these reasons, it is not possible to list an exact tire circumference. Approximate tire circumferences In order to accurately program a bicycle computer, we recommend a simple rolling test with the rider on the bicycle where a mark is made on the tire, and the distance between it's contact point with the ground is measured across one full revolution.

Question 2

Puncture protection levels explained

Accepted Answer

Schwalbe tires use several different puncture protection technologies, each suited to a different balance of weight, cost, and protection. | In general, more protection means more weight and a bit more rolling resistance, so the right choice depends on whether you're prioritizing speed or peace of mind. Here's what's under the tread on different tire lines:

${youtube}Schwalbe Puncture Protection Ratings

City and Tour Tires

|| Only tires with SMARTGUARD® and SMART DUALGUARD can call themselves Flat-Less. You can never completely rule out a flat tire. Against the typical puncture gremlins such as glass shards or goatheads with the Marathon Plus however, you are very well protected. With all Marathon Plus tires it is necessary to use a pressure gauge to adjust the air pressure. Due to the special design a pressure test by thumb is not sufficient.

For City and Tour Tires, Schwalbe has the following offerings: | Rating | Name | Description | | ---- | | 7 | Smart DualGuard | The safest puncture protection, typically found on wider tires (greater than 40mm)Made of highly elastic special rubber.4mm puncture protection insert plus two layers of nylon fabric (RaceGuard®).Features Flat-less technology. | | 7 | [SmartGuard](https://www.schwalbetires.com/bik

Question 3

Tire width and inner rim width compatibility

Accepted Answer

A tire's profile when mounted varies greatly on the width of the wheels rim. As mentioned in other articles, a wider inner rim width will yield a wider and flat profile. A narrower inner rim width will result in a voluminous shape that resembles a light bulb.

The ETRTO has recommendations for such combinations of tire and rim width. To optimize safety and performance, it is always recommended to stay within the highlighted range of acceptable widths: Tire and inner rim width combinations

Question 4

When is a tire worn out?

Accepted Answer

When the puncture protection belt or the carcass threads can be seen through the tread the tire has reached its wear limit and must be replaced. As puncture resistance also depends on the thickness of the tread layer, it may be useful to replace the tire sooner. The sidewalls of tires often fail before the tread is worn out. In most cases, this premature wear is due to prolonged use of the tire with insufficient pressure. Checking and re-pumping the inflation pressure at least once a month with a pressure gauge is most important.

For tires with a deep tread pattern that generate grip in loose terrain, like those used on a mountain bike, a worn out tire can lead to loss of grip and safety concerns. In such instances the user may wish to replace their tire even before the puncture protection belt or carcass threads begin to appear.

Question 5

Why are tires sometimes narrower than their listed size?

Accepted Answer

In order to ensure that tires have sufficient frame clearance, tire manufacturers generally prefer to keep production closer to the lower end of the permitted tolerance (+/- 2 mm). Once mounted, inflation pressure plays a major role in the tires measured width. With maximum inflation pressure the tire becomes wider than with low pressure. This continues until the tire is fully stretched out. Such a break-in period can require 40-50km of riding before the tire has stretched out to it's final width.

| It is not uncommon for flexible carcass constructions, such as radial tires, to stretch out 2-3mm during their break-in period. The final width will still sit within the tires ETRTO compliant tolerance.

It's Important to note that a tires measured width is directly affected by the internal rim width of the wheel it is mounted on. A larger internal rim width will yield a flatter cross-sectional tire profile. Conversely, a smaller internal rim width results in a tire profile that is more rounded. || The tire width is measured at the widest point, i.e. outside the shoulder lug.

See in the below tire schematics how a 40mm wide tire can be as narrow as 39mm on a 19mm internal width rim, but as wide as 45mm on a 25mm internal width rim: 40mm Tire Schematic on Various Rim Widths When upgrading a tire, one should consider the internal rim width of their wheel as this will di

Question 6

Common Valve Types

Accepted Answer

There are two valve types that have become market standard in North America and it is difficult to make any particular recommendation. The most important aspect is that the valve fits the rim valve hole and that an appropriate pump is available. Contrary to popular belief, major air retention differences are now a thing of the past. In any case, all Schwalbe valves provide excellent performance and are adapted to high-pressure use.

The Presta Valve (SV) is narrower than other valves (6 instead of 8 mm) and is always composed of metal. It needs a smaller rim hole and is therefore particularly well suited for narrow racing bike rims but is also common in tubeless setups. It is also approx. 4-5 g lighter than a Schrader valve.

||| Caution: Be aware that using Presta valve tubes on rims with larger valve holes (intended for Schrader Valves) often leads to a valve tear off when the sharp metal edges around the valve hole cut the valve stem off the tube.

A Presta valve can be locked manually with the knurled nut. Before inflating, the knurled nut must be loosened. First time users frequently have some problems. Also the thin top pin can be easily bent when attaching and removing the pump connector.
Should the Presta valve top pin become bent or damaged, it can be easily replaced with a new valve core. These are commonly carried at bike shops, and they can be easily unthreaded from the valve stem. ![Schwalbe Presta Valve](https://storage.crisp.chat/users/helpdesk/website/

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