GB2347393A - Tyres for land vehicles - Google Patents

Abstract

The tyre has embedded in its body (1) beneath the grooved tread (2) a strip (5) or other element which is of a colour different from that of the tread and luminous, for example fluorescent, the strip being arranged so that it is not visible when the tread depth is above a predetermined value but it becomes visible when the tread depth reaches that value as the tread wears away during use. A second similar strip but of a different colour may also be provided to indicate in the same way when the tread depth reaches a greater value.

Description

TYRES FOR LAND VEHICLES This invention relates to tyres for land vehicles.

In particular, the invention is concerned with a pneumatic tyre of the kind (hereinafter referred to as"the kind specified") comprising a body provided with a tread for contact with the ground, the tread being provided by an outer part of the tyre moulded of rubber, a rubber compound or other, like material in which is provided a series of grooves opening at the ground engaging face of the tyre.

Under U. K. law it is an offence to use a motor vehicle on the public roads fitted with any tyre having a tread depth (measured as the depth of the grooves over a predetermined area of the tread surface) below a specified minimum, currently 1. 6mm. Indeed motorists are advised in the interests of safety to replace tyres before the tread depth reaches this limit, usually at about 2mm depth. However, many motorists do not check their tyres as frequently as they should do, possibly because it involves kneeling down and looking under the vehicle and then it can be difficult to inspect the whole tread because it may be dark under the vehicle, and as a result a motorist can unknowingly be running a vehicle with an illegal tyre. Also, the police cannot check the legality of a vehicle's tyres without the vehicle being stationery, which often involves the motorist in the inconvenience of being stopped by the police.

The object of the present invention is to overcome or at least minimise these problems.

According to the invention there is provided a tyre of the kind specified in which the body incorporates a part which is located beneath at least a portion of the tread so that it is not visible when the tread depth of that portion is above a predetermined value but it becomes visible when the tread depth reaches that value as the tread wears away during use, the said part when visible differing in appearance from the remaining tread of the tyre.

The idea, therefore, is that the exposure to view of the said part of the tyre body will provide a warning that the tread depth has reached the said predetermined value. This may be the legal limit or a value above the legal limit such as a recommended limit for safety reasons, or the tyre body may incorporate a second, similar normally invisible part which is arranged to become visible when the tread depth reaches a value greater than the aforesaid predetermined value, this second part when visible differing in appearance from both the remaining tread and the first part (if the latter is exposed) whereby different warnings are given when the tread depth reaches the two values referred to.

The different appearance of the or each part may be achieved by making it of a colour different from the tread (and from the colour of the other part when two such parts are incorporated in the tyre).

Preferably the or each part is formed so as to be luminous when visible, for example fluorescent. This is a particularly advantageous aspect of the invention as it enables motorists to check their tyres in the dark. Also the or each part when exposed to view can be seen by the police and others when the vehicle to which the tyre is fitted, is in motion. Thus, if the or each part is exposed through only a portion of the tread, it will be seen to produce a stroboscopic effect as the tyre rotates making it particularly noticeable to a person in a vehicle travelling behind the vehicle to which the tyre is fitted.

The or each part or one of the two parts may comprise an element such as a strip of material embedded in the tyre body. Where there are two such elements they may be disposed one above the other in the tyre body.

The invention will now be described, by way of example, with reference to the accompanying drawing which is a perspective view, partly in section, of one embodiment of a tyre according to the invention.

The tyre illustrated in the drawing comprises a body 1 which is of a conventional construction in that it consists of a tread 2 supported by a carcass 3 (not shown in detail) made up of a number of belt plies incorporating cords.

The tread 2 is moulded from a rubber compound and is formed with a series of circumferential grooves 4 of a predetermined depth.

In accordance with the invention a strip of material 5 is embedded in the tyre, the strip extending across the whole width of the tread and around the whole circumference of the tyre. The material of the strip 5 is both luminous, for example fluorescent, and of a different colour compared with the colour of the tread 2.

The strip 5 is normally not visible but is arranged so that as soon as any portion of the tread 2 wears down to a predetermined depth being the appropriate legal limit, a part or parts of the strip become visible at the bottom of one or more of the grooves 4. This provides a warning that at least a portion of the tread has worn down to the legal limit and therefore the tyre should be replaced.

If desired, a further strip (not shown) similar to the strip 5 but of a different colour may also be embedded in the tyre above the strip 5 so that a part or parts of this further strip become exposed to view when the tread depth reaches a predetermined value greater than the legal limit which is recommended for safety reasons.

The invention includes any novel and inventive feature disclosed herein are either alone or in combination with any one or more other such features.

Also, many detailed modifications are possible and, in particular, the scope of the invention is not to be construed as being limited by the illustrative example or by the terms and expressions used herein merely in a descriptive or explanatory sense.

Claims (9)

1. CLAIMS 1. A tyre of the kind specified in which the body incorporates a part which is located beneath at least a portion of the tread so that it is not visible when the tread depth of that portion is above a predetermined value but it becomes visible when the tread depth reaches that value as the tread wears away during use, the said part when visible differing in appearance from the remaining tread of the tyre.
2. 2. A tyre as claimed in Claim 1 wherein the body incorporates a second part which is located beneath at least a portion of the tread so that it is not visible when the tread depth of that portion is above a second value greater than said predetermined value but which is arranged to become visible when the tread depth reaches that second value, this second part when visible differing in appearance from both the remaining tread and the first part (if the latter becomes visible).
3. 3. A tyre as claimed in Claim 1 or 2 wherein the different appearance of the or each part is achieved by making it of a colour different from the tread (or from the colour of the other part when two such parts are incorporated in the tyre).
4. 4. A tyre as claimed in Claim 1, 2 or 3 wherein the or each part is formed so as to be luminous when visible.
5. 5. A tyre as claimed in Claim 4 wherein the or each part is fluorescent.
6. 6. A tyre as claimed in any one of the preceding claims wherein the or each part or one of the two parts comprises an element embedded in the tyre body.
7. 7. A tyre as claimed in Claim 6 wherein the said element is a strip of material.
8. 8. A tyre as claimed in Claim 6 or 7 which has two said elements wherein said elements are disposed one above the other in the tyre body.
9. 9. A tyre substantially as herein described with reference to the accompanying drawing.