WO2002086417A1

WO2002086417A1 - Improvements in or relating to tyre tread depth gauges

Info

Publication number: WO2002086417A1
Application number: PCT/GB2002/001776
Authority: WO
Inventors: Pietro Vincenzo Lo Giudice
Original assignee: Pietro Vincenzo Lo Giudice
Priority date: 2001-04-24
Filing date: 2002-04-17
Publication date: 2002-10-31
Also published as: GB2390681A; GB2390681B; WO2002086417B1; GB2374933A; GB0324874D0; GB0109979D0

Abstract

A tread depth gauge is disclosed for use in measuring the depth of tread on a tyre, such as, for example, a conventional motor vehicle tyre. The depth gauge is provided with engaging means configured to engage releasably the air valve of a tyre thereby to releasably secure the depth gauge to the air valve in a storage position when the gauge is not in use.

Description

IMPROVEMENTS IN OR RELATING TO TYRE TREAD DEPTH GAUGES

THE PRESENT INVENTION relates to a tread depth gauge for use in measuring the depth of tread on a tyre such as, for example, a conventional pneumatic tyre as used around each wheel of a motor vehicle. More particularly, the present invention relates to a tread depth gauge which can be easily and conveniently stored upon the air valve of a conventional tyre when not in use.

As is commonly known, conventional motor vehicle tyres are made from rubber or rubber-type materials and are provided with a raised tread pattern therearound to bear against a road surface as the motor vehicle is driven along the road. The raised tread pattern defines a plurality of channels between the road surface and the main body of the tyre to assist in directing water which may be lying upon the road surface, away from the contact area between the tyre and the road surface to avoid the risk of the motor vehicle skidding in wet road conditions.

Throughout the useful life of conventional tyres of the type described above, the depth of tread provided typically reduces progressively as the tyre is subjected to wear through use. It is commonly known that as the tread depth reduces in this way, the effectiveness of the channels defined between the body of the tyre and the road surface, in directing water away from the contact area between the tyre and the road surface, reduces. It is therefore common for the relevant regulatory bodies of most countries to set minimum safe limits for the depth of tread on motor vehicle tyres. For example, the minimum tread depth in the United Kingdom is presently 1.6mm.

It will therefore be clear that throughout the useful life of a motor vehicle tyre, the actual depth of tread must be monitored to ensure that the depth remains above the relevant legal minimum limit. It is therefore common to provide simple tyre tread depth gauges which serve to measure, or at least assess the depth of tread still existing on a tyre.

A common type of known tread depth gauge comprises a main cylindrical body portion telescopically receiving a graduated plunger, the end of the plunger being sized so as to fit between raised parts of the tyre tread. With the end of the cylindrical body portion bearing against the raised tread on the tyre, the plunger is pressed axially with respect to the body portion so that its end passes between the respective parts of the tread and bears against the main body of the tyre, whereafter the gauge is removed from the tyre and the depth of the tread remaining on the tyre can be read from the respective positions of the end of the main body portion and the graduations on the movable plunger.

However, tyre pressure gauges are usually relatively small tools within typical automotive tool kits and hence can quite easily become separated from a tool kit, misplaced or even lost entirely. The present invention therefore seeks to provide an improved tyre tread depth gauge which is less likely to become misplaced or lost. Accordingly, the present invention provides a tread depth gauge for use in measuring or assessing the depth of tread on a tyre, the gauge comprising engaging means configured to engage releasably the air valve of a tyre thereby to secure the gauge releasably to the air valve in a storage position when the gauge is not in use.

Preferably, the engaging means comprises an aperture sized to receive the air valve therethrough.

Advantageously, the aperture is sized to engage the air valve as an interference fit.

Conveniently, the aperture is sized so as not to pass over a valve cap engaged with the air valve.

Preferably, the tread depth gauge has a substantially angular configuration.

Advantageously, the tread depth gauge has indicia provided on at least one surface of the gauge.

Conveniently, the tread depth gauge is moulded from plastics material.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, an embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which :-

FIGURE 1 is a schematic plan view of a tread depth gauge in accordance with the present invention; FIGURE 2 is a schematic perspective view of the tread depth gauge of the present invention, illustrating the gauge being positioned over a tyre air valve; and

FIGURE 3 is a schematic side elevational view, illustrating the tread depth gauge of the present invention, releasably secured to the air valve of a tyre, in a storage position.

A tyre tread depth gauge 1 according to the present invention is illustrated schematically in plan form in Figure 1. The depth gauge 1 is illustrated in the form of an annular-shaped plastic moulding defining an inner circular edge 3 and an outer circular edge 4. Whilst the annular configuration illustrated is the most preferred configuration for the tread depth gauge, it will, of course, be appreciated that other configurations could also be adopted, without departing from the scope of the present invention. Also, it should be appreciated that whilst it is preferred to mould the depth gauge of the present invention from plastics material, this is not an essential requirement of the present invention and the depth gauge could instead, for example, be produced as a metal sheet stamping.

The annulus 2 of the depth gauge preferably has a thickness of several millimetres. It is essential that the annulus, which is preferably substantially planar, is thin enough to allow the outer circular edge 4 to be inserted between two parts of the tread of a conventional motor vehicle tyre. It is therefore proposed that a typical embodiment of the present invention will have a thickness of between 1 and 3 millimetres.

As will be appreciated, the annulus 2 defines a pair of opposed faces 5 (only one illustrated in Figure 1). One or both of these faces will typically be moulded, printed, stamped, or engraved with indicia 6 which could include, for example, instructions for use of the device in one or more languages. Additional advice, regarding for example tyre care generally, could also be provided on one of the surfaces 5 in a similar manner.

As illustrated in Figure 1, at least one surface 5 of the annulus 2 is provided with a reference line 7 which could be moulded, printed, stamped or etched onto the surface as appropriate. The reference line 7 could also, of course, be moulded into the surface 5 of the annulus, in the event that the annulus 2 is moulded from plastics material or the like.

The reference line 7 is provided so as to be spaced from the outermost edge 4 of the annulus 2 by a maximum distance d which will be equal to the relevant minimum legal tyre tread depth, for example, 1.6 mm in the case of the United Kingdom. In use, therefore, the tread depth gauge 1 is simply held by a person using the device and its outermost edge 4 is inserted between respective parts of the tread of a tyre so that the outer edge 4, in the region of the reference line 7, is received within the channel defined between the respective parts of the tyre tread. The gauge 1 is inserted between the tread of a tyre in this manner until the outermost edge 4 of the annulus 2 bears against the circumferential surface of the tyre from which the tread extends. In this position, it is then possible visually to asses the depth of the remaining tread on the tyre. For example, if the tread on the tyre projects past the reference line 7 spaced from the outermost edge 4 of the annulus 2, then it will be clear that the tread of the tyre is deeper than the required minimum legal limit d. If, on the other hand, the tread of the tyre does not project past the reference line 7, such that the reference line 7 is still visible over the tread of the tyre, then it will be clear that the remaining tread depth is less than the minimum legal requirement d, in which case the tyre should be replaced. The reference line 7 is indicated in Figure 1 as being a substantially straight line. However, it should, of course, be appreciated that the reference line 7 could instead take the form of a curved line forming part of a circle centred on the same point as the circle defining the outermost edge 4 of the annulus 2, but having a radius less than the radius of the circle defining the outermost edge 4, by a distance d. Of course, the reference line 7 could take the form of a complete circle of this nature.

Furthermore, it is also proposed that a variant of the invention could be configured to provide a more accurate quantitative measurement of the remaining tread depth on a tyre, by the provision of a graduated scale such as that illustrated schematically by reference numeral 8 in Figure 1.

It should be appreciated that the overall diameter of the annulus 2 illustrated in Figure 1 is not essential, providing that the overall size of the gauge is convenient for manual manipulation between the fingers of a person using the device. However, the diameter of the innermost circular edge 3 of the annulus 2, is more important. This is because the aperture 9 which is defined through the annulus 2 by the innermost circular edge 3, serves as engaging means effective to secure the depth gauge of the present invention releasably upon the air valve 10 (see Figures 2 and 3) of a conventional tyre.

The air valves of conventional tyres are typically provided in the form of elongate tubular arrangements which, when the tyre is mounted upon a motor vehicle wheel, extend through an aperture in the body of the wheel so as to extend substantially radially inwardly from the outer rim of the wheel. Typically, tyre air valves 10 are approximately 1 to 2 inches in length and have a tapered frusto-conical outer surface 11 which is typically wider at the end passing through the body of the vehicle wheel, than the end spaced radially inwardly therefrom. The opposite end of the air valve 10 is provided with an externally screw-threaded spigot 12 which is configured to receive threadedly a conventional air valve cap 13 (as illustrated in Figure 3) to protect the air valve 10, and help prevent leakage of air therethrough. Typically, the operative components of the air valve 10 (namely the valve seat and movable valve member) are provided in the region of the spigot 12 which has a sealable air passage therethrough. However, for the purposes of the present discussion, it should be appreciated that the term "air valve" is intended to refer to the elongate configuration generally, as illustrated in Figures 2 and 3.

Figure 2 illustrates the annulus 2 of the tread depth gauge 1 being mounted upon an upstanding air valve 10 of the type described above. As illustrated, the valve cap 13 has been removed from the externally screw- threaded spigot 12, to allow the central aperture 9 of the annulus 2 to be passed over the uppermost end of the air valve 10. The central aperture 9 of the annulus 2 is sized such that further downward movement of the annulus 2 with respect to the air valve 10, results in a point being reached at which the innermost circular edge 3 of the annulus 2 bears against the external frusto- conical surface 11 of the air valve 10 (by virtue of the taper of the air valve 10). This position is illustrated generally in Figure 3. It will be appreciated that the sizing of the central aperture 9 is such that the annulus 2 of the depth gauge 1 engages the outermost surface of the air valve 10 as an interference fit. In fact, most conventional tyre air valves 10 are provided with an elastomeric outer coating which will serve to improve this interference fit between the annulus 2 and the air valve 10.

It will therefore be appreciated that the depth gauge of the present invention is configured for convenient mounting and securement upon a tyre air valve 10 when the gauge is not in use in measuring or assessing the depth of tread remaining on the tyre. The aforementioned engagement between the depth gauge 1 and the air valve 10 will usually be sufficient to prevent subsequent disengagement from the air valve 10 as the tyre and associated wheel of the motor vehicle rotate as the vehicle is driven. This is because the centrifugal forces applied to the depth gauge 2 when mounted upon the air valve will act along a line substantially coincident with the longitudinal axis of the air valve 10 outwardly from the centre of the wheel. Thus, as the tyre and associated wheel rotate, the depth gauge 2 mounted upon the air valve 10 will be urged into more positive engagement with the outermost surface of the air valve 10 by virtue of the paper of the air valve 10.

However, in order to safeguard against accidental disengagement of the depth gauge 1 of the air valve 10, for example through inadvertent knocking when the wheel and associated valve 10 are stationary, the central aperture 9 is sized so as to have a maximum dimension smaller than the outer diameter of the air valve cap 13 illustrated in Figure 3. Thus, once the depth gauge 1 of the present invention is mounted over the air valve 10 as described above, and moved into secure engagement therewith by virtue of the interference fit therebetween, the valve cap 13 can be replaced upon the externally screw- threaded spigot. Thereafter, even if the innermost edge 3 of the annulus 2 becomes disengaged from the external surface 11 of the air valve 10, the annulus 2 will be held captive on the air valve 10 by virtue of the air valve cap 13.

It will therefore be appreciated that the above described tread depth gauge falling within the scope of the present invention, serves to solve the problem of providing a tool suitable for measuring or assessing the depth of tread on a tyre, which can be conveniently and securely stored when not in use. In the present specification "comprises" means "includes or consists of and "comprising" means "including or consisting of.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A tread depth gauge for use in measuring or assessing the depth of tread on a tyre, the gauge comprising engaging means configured to engage releasably the air valve of a tyre thereby to secure the gauge releasably to the air valve in a storage position when the gauge is not in use.

2. A tread depth gauge according to claim 1, wherein the engaging means comprises an aperture sized to receive the air valve therethrough.

3. A tread depth gauge according to claim 2, wherein the aperture is sized to engage the air valve as an interference fit.

4. A tread depth gauge according to claim 2 or claim 3, wherein the aperture is sized so as not to pass over a valve cap engaged with the air valve.

5. A tread depth gauge according to any preceding claim having a substantially annular configuration.

6. A tread depth gauge according to any preceding claim having indicia provided on at least one surface of the gauge.

7. A tread depth gauge according to any preceding claim moulded from plastics material.

8. A tread depth gauge substantially as hereinbefore described with reference to and as shown in the accompanying drawings. Any novel feature or combination of features disclosed herein.