*Size: A fully inflated tire mounted on a rim takes a considerable space to store. It would also require a large opening access for it to be removed when needed. For example, if it were stored in the basement area of an “A” class coach, it may required an over sized access door to allow it to be removed.
*Weight: The weight of a tire and steel rim varies greatly with the size and type, but it is a substantial weight. This extra weight adds to the GVW (Gross Vehicle Weight) which reduces the allowable carrying weight and potentially increases fuel consumption.
*Cost: An additional tire and rim raises the manufacturer’s wheel set costs almost 17%, and that is not even addressing any possible hold down hardware. In addition to this, the spare yields little when viewed as an added value by potential purchasers. So, if buyers don’t know, or for that matter, care, why supply it.
*Not User Friendly: It may be quite questionable that larger spares are user serviceable. The average motor home owner is not equipped to replace the wheel in the field. Firstly, a suitable bottle jack is generally not included. Secondly, the strength to handle the wheel and remove the lug nuts, may prove a challenge that may exceed the ability of the normal owner.
Many people choose to carry an un-mounted, tire only. This is lighter and stores much better as it can be somewhat flattened. A tire service can quickly swap the flat or damaged one and mount the new. This was my answer also when I had my last coach. The advantages to this solution are, guarantying a perfect match, no waiting and reducing costs of both the tire and shipping. After all, getting a reasonable match is a challenge in many areas, particularly if the tire is a “70” series. This is due to the fact that low profile tires are generally not popular in the commercial truck market and therefore not readily available. Another big advantage to this is, once done, it is final as the tire is mounted on the exact rim involved. A two axle motor home equipped with aluminum wheels has three different wheel configurations. Aluminum deep dish (rear outer), reverse dish (front) and the inner steel. There are three types because aluminum wheels are generally polished only on one side, depending on the intended position.
So, why are people now willing to accept the “no spare”? Are they having less tire issues? Perhaps. Tire monitoring systems, similar to the one shown in the picture, have, and are, becoming very popular. There is no secret that these electronic monitors have substantially reduced on the road tire issues by warning the operator prior to it being a big problem. This early warning information can advise both the individual tire’s current temperature and pressure in real time.
Well, mounted spare, un-mounted spare tire only, or no spare at all. While many models will come without, some may wish to add one anyway. What’s your preference?
With Some Spare Thoughts – Lug_Nut – Peter Mercer