Axle spacing is another consideration that must be taken into account when looking at Federal weight compliance. To protect bridges, the number and spacing of axles carrying the vehicle load must be calculated. Thus, a bridge weight formula is also applied to commercial vehicles in determining their compliance with Federal weight limits. The Federal bridge formula applies when the gross weight on two or more consecutive axles exceeds the limitations of the formula, except that two consecutive sets of tandem axles may carry a gross load of 34,000 lbs. pounds each if the overall distance between the first and last axle is 36’ or more.

W = 500(LN/N-1 + 12N + 36)

W = Overall gross weight on any group of 2 or more consecutive axles to the nearest 500 pounds.
L = Distance in feet between the extreme of any group of 2 or more consecutive axles.
N = Number of axles in the group under consideration.

Exception to the Bridge Weight Formula

Federal law (23 U.S.C. 127) includes an exception to the Bridge Formula and the Bridge Table—two consecutive sets of tandem axles may carry 34,000 lbs. pounds each if the overall distance between the first and last axles of these tandems is 36’ or more. For example, a five-axle tractor-semitrailer combination may carry 34,000 lbs. pounds both on the tractor tandem (axles 2 and 3) and the trailer tandem (axles 4 and 5), provided axles 2 and 5 are spaced at least 36’ apart. Without this exception, the Bridge Formula would allow an actual weight of only 66,000 lbs. to 67,500 pounds on tandems spaced 36 to 38’ apart.

The Federal Bridge Weight Chart

2
axles
3
axles
4
axles
5
axles
6
axles
7
axles
8
axles
9
axles
Less than 8’3″ 34,000 34,000
More than 8’4″ 38,000 42,000
9 39,000 42,500
10 40,000 43,500
11 44,000
12 45,000 50,000
13 45,000 50,500
14 46,500 51,500
15 47,000 52,000
16 48,000 52,500 58,000
17 48,500 53,500 58,500
18 49,500 54,000 59,000
19 50,500 54,500 60,000
20 51,000 55,500 60,500 66,000
21 51,500 56,000 61,000 66,500
22 52,500 56,500 61,500 67,000
23 53,000 57,500 62,500 68,000
24 54,000 58,000 63,000 68,500 74,000
25 54,500 58,500 63,500 69,000 74,500
26 55,500 59,500 64,000 69,500 75,000
27 56,000 60,000 65,000 70,000 75,500
28 57,000 60,500 65,500 71,000 76,500 82,000
29 57,500 61,500 66,000 71,500 77,000 82,500
30 58,500 62,000 66,500 72,000 77,500 83,000
31 59,000 62,500 67,500 72,500 78,000 83,500
32 60,000 63,500 68,000 73,000 78,500 84,500 90,000
33 64,000 68,500 74,000 79,000 85,000 90,500
34 64,500 69,000 74,500 80,000 85,500 91,000
35 65,500 70,000 75,000 80,500 86,000 91,500
36 66,000 70,500 75,500 81,000 86,500 92,000
37 66,500 71,000 76,000 81,500 87,000 93,000
38 67,500 71,500 77,000 82,000 87,500 93,500
39 68,000 72,500 77,500 83,500 88,500 94,000
40 68,500 73,000 78,000 84,000 89,000 94,500
41 69,500 73,500 78,500 84,500 89,500 95,000
42 70,000 74,000 79,000 84,500 90,000 95,500
43 70,500 75,000 80,000 85,000 90,500 96,000
44 71,500 75,500 80,500 85,500 91,000 96,500
45 72,000 76,000 81,000 86,000 91,500 97,500
46 72,500 76,500 81,500 87,000 92,500 98,000
47 73,500 77,500 82,000 87,500 93,000 98,500
48 74,000 78,000 83,000 88,000 93,500 99,000
49 74,500 78,500 83,500 88,500 94,000 99,500
50 75,500 79,000 84,000 89,000 94,500 100,000
51 76,000 80,000 84,500 89,500 95,000 100,500
52 76,500 80,500 85,000 90,500 95,500 101,000
53 77,500 81,000 86,000 91,000 96,500 101,500
54 78,000 81,500 86,500 91,500 97,000 102,000
55 78,500 82,500 87,000 92,000 97,500 102,500
56 79,500 83,000 87,500 92,500 98,000 103,000
57 80,000 83,500 88,000 93,000 98,500 104,000
58 84,000 89,000 94,000 99,000 104,500
59 85,000 89,500 94,500 99,500 105,000
60 85,500 90,000 95,000 100,500 105,500

We are committed to providing expert-level guidance to truckers, transport agencies, and those seeking to secure their permits. It is our mission to keep you both safe and legal as you haul your loads. We pride ourselves on being fast and affordable. Let us support your fleet and learn what it means to work with America's most liked permit agency.

Donald Beeman, President Donald Beeman, President

Coast 2 Coast Trucking Permits

5410 Homberg Drive, Suite 33 Knoville, TN 37919

Hours of Operation

Monday - Friday
7:00 AM - 5:30 PM EST