A hand-held device for obtaining a three-dimensional topological surface profile of a tire, the device comprising: a base comprising an aperture; a light source arranged in use to generate an elongate pattern of light, and to project said pattern through the aperture onto a rolling surface of the tire; a detector arranged to image a region of the rolling surface of the tire; a plurality of pairs of guide wheels mounted on respective axles mounted on the base, wherein the guide wheels on adjacent axles are linked by gears; and a rotary encoder arranged to generate a signal corresponding to rotation of an axle.

An ergonomic and rider-friendly auto-balancing personal transportation device. The device may have a central wheel structure with one or more tires and deployable foot platforms located on both sides of the central wheel structure. The platforms may be linked to a handle, such that lifting the handle retracts the foot platforms and releasing the handle may deploy them. The tire size and platform size may be set so that the device is easy to step on to, and the distance to ground when dismounting is reduced. Dual tire and single wider tire embodiments are disclosed as are other features and embodiments.

The Dual Tire Shield of the invention mounts between dual tires and helps to prevent debris from getting into the gap between dual tires and/or damaging the tires when it does so. In some embodiments it can also serve as a runflat for dual tires. Debris can become wedged between the sidewalls of dual tires that face each other, or inner sidewalls of such tires. The dual tire shield prevents debris from getting stuck between the inner sidewalls of the dual tires and thereby prevents flats caused by sidewall puncture or bead de-seating due to such debris. The device accomplishes this by: Blocking debris from entering the gap between duals and/or prevent debris from being wedged in the gap; keeping such debris from contact with one or both of the tires even if wedged therebetween; and/or ejecting debris from between the tires. Further, the dual tire shield may be made rigid enough and/or include rigid portions so as to act as a runflat in case a tire goes flat regardless of the reason.

The Dual Tire Shield of the invention mounts between dual tires and helps to prevent debris from getting into the gap between dual tires and/or damaging the tires when it does so. In some embodiments it can also serve as a runflat for dual tires. Debris can become wedged between the sidewalls of dual tires that face each other, or inner sidewalls of such tires. The dual tire shield prevents debris from getting stuck between the inner sidewalls of the dual tires and thereby prevents flats caused by sidewall puncture or bead de-seating due to such debris. The device accomplishes this by: Blocking debris from entering the gap between duals and/or prevent debris from being wedged in the gap; keeping such debris from contact with one or both of the tires even if wedged therebetween; and/or ejecting debris from between the tires. Further, the dual tire shield may be made rigid enough and/or include rigid portions so as to act as a runflat in case a tire goes flat regardless of the reason.