45 C.F.R. § 84.74 – Mobility devices.

(a) Use of wheelchairs and manually-powered mobility aids. A recipient shall permit individuals with mobility disabilities to use wheelchairs and manually-powered mobility aids, such as walkers, crutches, canes, braces, or other similar devices designed for use by individuals with mobility disabilities in any areas open to pedestrian use.
(b) Use of other power-driven mobility devices—(1) Requirement. A recipient shall make reasonable modifications in its policies, practices, or procedures to permit the use of other power-driven mobility devices by individuals with mobility disabilities, unless a recipient can demonstrate that the class of other power-driven mobility devices cannot be operated in accordance with legitimate safety requirements that a recipient has adopted pursuant to § 84.68(h).
(2) Assessment factors. In determining whether a particular other power-driven mobility device can be allowed in a specific facility as a reasonable modification under paragraph (b)(1) of this section, a recipient shall consider—
1. (i) The type, size, weight, dimensions, and speed of the device;
2. (ii) The facility's volume of pedestrian traffic (which may vary at different times of the day, week, month, or year);
3. (iii) The facility's design and operational characteristics (e.g., whether its program or activity is conducted indoors, its square footage, the density and placement of stationary devices, and the availability of storage for the device, if requested by the user);
4. (iv) Whether legitimate safety requirements can be established to permit the safe operation of the other power-driven mobility device in the specific facility; and
5. (v) Whether the use of the other power-driven mobility device creates a substantial risk of serious harm to the immediate environment or natural or cultural resources, or poses a conflict with Federal land management laws and regulations.
6. (c) Inquiry about disability—(1) Requirement. A recipient shall not ask an individual using a wheelchair or other power-driven mobility device questions about the nature and extent of the individual's disability.
7. (2) Inquiry into use of other power-driven mobility device. A recipient may ask a person using an other power-driven mobility device to provide a credible assurance that the mobility device is required because of the person's disability. A recipient in permitting the use of an other power-driven mobility device by an individual with a mobility disability shall accept the presentation of a valid, State-issued, disability parking placard or card, or other State-issued proof of disability as a credible assurance that the use of the other power-driven mobility device is for the individual's mobility disability. In lieu of a valid, State-issued disability parking placard or card, or State-issued proof of disability, a recipient shall accept as a credible assurance a verbal representation, not contradicted by observable fact, that the other power-driven mobility device is being used for a mobility disability. A “valid” disability placard or card is one that is presented by the individual to whom it was issued and is otherwise in compliance with the State of issuance's requirements for disability placards or cards.