The minimum school bus dimensions and specs are set down by each state, and these must be met by manufacturers. The following are the specifications for Idaho type C buses. These do not necessarily apply to those of other states.
For a seating capacity of 41, the wheelbase should be 165”-193”, the frt. axle cap 8,000 lbs and the rear axle cap 17,500 lbs. The frt. spring cap at ground is 5,000. For a seating capacity of 53, the wheelbase must be 214”-218”.
The frt. axle cap is 10,000 lbs, the rear axle cap 19,000 lbs and the frt. spring cap at ground is 5,000. For school bus dimensions with a seating capacity of 66, the wheelbase is 252”-255”. The frt. axle cap Is 10,000 lbs. The rear axle cap Is 19,000 lbs and the frt. spring cap at ground 5,000.
For a 72 seating capacity of 72, the wheelbase is 273”-277”. The frt. axle cap is 10,000 lbs and the rear axle cap is 21,000 lbs. The frt. spring cap at ground is 5,000.
For a 78 seating capacity, the wheelbase is 273”-278”. The frt. axle cap is 10,000 lbs and the rear axle cap is 21,000 lbs. The frt. spring cap at ground is 5,000.
Brakes, Bumpers and Road Control
Regardless of the school bus dimensions, the brake specifications are 15.0 X 4.0 inches (air – front outboard drum) and 16.5 X 7.0 inches (air – rear outboard drum). The front bumper must be at least 3/16” thick and a minimum 8” wide.
The material has to be pressed steel or something like it. The engines must be electronically controlled. The engines need to be set to a maximum speed limit of 170 mph.
Turning Radius and Tires
A chassis that has a 264 inch wheelbase or less needs to have a right and left turning radius of 42 ½ ft maximum. If the wheelbase is 265 inches or more, the turning radius must be 55 ½ ft maximum curb to curb.
Whatever the school bus dimensions, there will always be six tires. Two are to be put in front and four at the back. These tires have to be the tubeless type and with steel belted radial construction. The tires have to be size 11R22.5.
The ply rating must be sixteen- (16) minimum with an H load range. The chassis have to be fitted with six wheels 8.25 inches wide. The chassis must have an extra rim/wheel.
Seating Capacity and Body Length
For 41-42 seating capacity, the body length must be 244-268 inches; for 53-54 seats, it is 302-322 inches and for 65-66, it is 358-376 inches. If the seating capacity is 71-72, the body length must be 387-402 inches and for 77-78, 402-410 inches.
The step risers have a maximum height of 10 5/8 inches. The floor must be layered with elastomeric covering at least 1/8 inches thick.
The school bus dimensions as specified here are the minimum requirements. Manufacturers often exceed those figures. Again, these specs are not representative of buses used in other states or countries.