According to the definition of a school bus, found under the US Department of Transportation guidelines for a school bus, any vehicle that carries more than 10 or more passengers including the driver is a bus. For such large vehicles that carry so many passengers, why are there so few wheels? How many wheels does a bus have?
Technically, a school bus only has four wheels, although there are six tires mounted. Two tires go on the front axle while four tires sit on the rear axle. That’s not all, as there are other types of school buses, some of which have more or fewer than six tires.
A small school bus might only have four tires, with two wheels on the front and two on the back, four tires total mounted onto four wheels. A school bus is large and heavy enough that it generally requires more wheels than a traditional van, and the driver must obtain a Class B Commercial Driver’s License (CDL) to drive one.
Why does a long school bus have only six tires?
The weight and the length of the school bus determine how many tires go on it. Even in a large school bus, there are only two axles, and you can only cram so many tires on each one.
The front axle is where all the turning left or right happens, so there’s no reason to put four tires up there, as that would be unwieldy. The rear is where most of the weight is, and it’s also where most of the centrifugal forces occur. So, it makes sense to add a couple of tires to the rear axle and put more rubber real estate on the asphalt for better control and handling.
A short school bus lacks the weight and the length to necessitate the two more tires on the back, so you typically only see two on the back and two on the front. It’s much more like a traditional van that’s converted to accommodate a limited number of students.
There are six types of school buses
Since we’re on the tire discussion, you might hear about the fact that there are more than one or two school bus types riding around out there. While there is nothing exceptional about how many wheels they have, they’re worth listing just so you know how many wheels/tires each one has.
1. School bus type A
Type A school buses are your traditional short bus, with four side windows, a hydraulic door, an emergency exit in the back, and two windows on either side of the driver. These types of buses may have only four wheels, but some will have six tires, and some will have four tires.
A school bus is classified as a bus that carries more than 10 students with a GVWR (Gross Vehicle Weight Rating) of 10,000lbs or less.
2. School bus type B
A type B school bus is a specific type of school bus that is designated for “specific school district needs”. It is one of the rarer school bus types, and it often has six tires, though it is roughly half the length of a standard school bus. The GVWR for a Type B is more than 10,000lbs but isn’t specific on a maximum.
3. School bus type C
This is your traditional school bus and the one that you are more likely to see rolling down the street on weekday mornings. The GVWR is over 10,000lbs, and it typically has two tires on the front axle and 4 tires on the rear axle.
4. School bus type D
While this isn’t the traditional school bus that everyone is used to seeing, the Type D school bus is becoming more prevalent in recent years. Roughly the same size as a Type C school bus, Type D has a GVWR of over 10,000lbs with two tires in the front and four in the rear.
The big difference between this type of school bus and the Type C school bus is that the front tires are located behind the driver, and the front of the bus is completely flat.
5. Multifunctional school bus
These school bus types aren’t for transporting kids to and from school. They are designed for school activities transportation, and they are exactly the same as the Type C school bus, with the same number of tires and the same placement.
The only difference between a multifunctional bus and a Type C bus is a multifunctional bus doesn’t have to be painted the traditional yellow/orange of a Type C bus. It can be any color but is most often white.
6. School van type
School vans are the closest you can get to a regular van that has been painted yellow/orange. You even enter it like you would a two-door van, and it only has four tires that ride on two axles, two in the front and two in the rear.
What size are school bus tires?
The typical school bus tire that you will find on most bus types is a 10R22 tire, which has a 10” width and a 22.5” height. Some school buses will have even larger tires at 11R22.5, which is 11” in width and 22.5” in height.
A full set of tires will set a school district back anywhere between $2,500 and $3,000. If it’s a set of 6, that can easily come to $500 a pop. School bus tires, even though they carry around our kids, are merely conventional, low-profile tires.
However, school bus tires are usually pretty resilient and can last quite a long time. Their sidewalls are a little shorter, so they can look a bit narrow on the large wheels that school buses use. School bus tire sidewalls are also very stiff, so they’re difficult to puncture from the side.
A properly maintained school bus tire will last up to ten years, which is guaranteed to be much longer than any tire that the rest of us are used to. Some will run their tire tread down until the inner wires are showing and still won’t give half of the lifespan out of their tires that a school bus will.
What kind of tires do school buses use?
Since schools are federally funded (and state-funded on some levels, depending on the school), they go by what the federal or state government determines are the best brands in school bus tires.
- Goodyear Tire and Rubber Company
- Double Coin Holdings
- Hankook Tire America Corporation
- Michelin Americas Truck Tires
Double Coin Holdings
Double Coin Holdings sounds like one of those bizarre stocks that show up next to a more familiar stock, however, they are a legitimate tire company. They also happen to be the ones that are tapped most for specialty school buses.
They sell the RT 500 tires that the government determined to be the best tire for that sort of bus type, which is the Type B bus.
Michelin Americas Truck Tires
They may indicate that they sell truck tires, but since a school bus uses tires similar to 18-wheelers, Michelin has the right tire for the job. Specifically, Michelin sells the XDN2 Drive Axle tire, which is the primary choice for most of your traditional school buses.
Hankook Tire America Corp
The tires that schools go for here are the AH24, AH12, and AH11 tires. These tires are supposedly very tough tires that are highly resistant to cuts, tears, and punctures, so they make plenty of sense for a variety of school bus use.
Goodyear Tire and Rubber Co.
Goodyear is probably the most readily recognizable name on the list. With their G182 RSDand G661 HSA tires, Goodyear provides what they call “Tredlock Technology” to school buses all over the country.
Why are rear school bus tires located close to the middle?
One of the more noticeable things about a school bus is the fact that there are a lot of school buses hanging off the back, well beyond the four rear tires. Why is that? Well, it all has to do with how the school bus handles a turn.
The location of the rear tires closer to the middle allows the school bus to cut a tighter turn. This is especially true when traveling through neighborhoods with narrow or even one-lane streets.
If they were located farther back, the school bus would be forced to take a massively wide turn, and it would probably still end up jumping the curb. The location is ideal so that every time a bus takes a left or right turn, it doesn’t end up way out into the opposing lane.
Despite their long length, most school buses will never have more than six tires (four wheels), with two on the front axle and four tires on the rear axle. Sure, there are buses out there with more, but they are never going to be classified as school buses.
While some school buses have fewer tires than others, the traditional school bus that is instantly recognizable almost anywhere in the country, maybe even the world, will always have six tires.