Axle Weight Limits: Steer, Drive, and Tandem Explained
Being under 80,000 lbs total does not mean you are legal. Individual axle weights are checked separately — and getting grossed out on a single axle is one of the most common violations at weigh stations. This guide breaks down every axle limit and shows you how to fix common overweight scenarios.
Ahmad Qazi
Founder & CEO, O Trucking LLC
Fact-Checked by O Trucking Editorial Team
Written by Ahmad Qazi, founder of O Trucking LLC, drawing on 9+ years dispatching for owner-operators. Learn more about us.
O TruckingAxle Weight Limits: Steer, Drive, and Tandem Explained (2026)
Key Takeaways
- Single axle limit is 20,000 lbs; tandem axle limit (drive or trailer) is 34,000 lbs federally.
- Steer axles have no specific federal number — they are capped by tire ratings, typically 12,000-14,000 lbs.
- Maximum gross vehicle weight is 80,000 lbs, subject to the federal bridge formula based on axle spacing.
- Axle weights and total gross weight are independent checks; being under 80,000 lbs does not make you legal if one axle group is over.
- Sliding tandems redistributes weight between axle groups; each hole (about 2 inches) moves roughly 250-500 lbs.
- Always reweigh on a CAT scale after any fifth-wheel or tandem adjustment to confirm every axle is legal.
The Three Axle Groups
A standard 5-axle tractor-trailer has three axle groups, each with its own weight limit:
Steer Axle — ~12,000-14,000 lbs
The front axle of the tractor. No specific federal limit, but constrained by tire ratings. Standard steer tires are rated for 6,150 lbs each (12,300 lbs total). Premium steer tires go up to 7,000 lbs each (14,000 lbs total). Most states enforce limits in this range.
Drive Tandem — 34,000 lbs
The two rear axles of the tractor. Federal limit is 34,000 lbs for the tandem (two axles with 40-96 inch spacing). Individual drive axles are limited to 20,000 lbs each. Drive tandems carry the engine and much of the cargo's forward weight.
Trailer Tandem — 34,000 lbs
The two rear axles of the trailer. Same 34,000 lb tandem limit. Trailer tandems are typically slidable — meaning you can adjust their position to redistribute weight between the drive and trailer axle groups.
Federal Axle Weight Limits at a Glance
Here is the quick-reference table for a standard 5-axle tractor-trailer under federal limits. These are the numbers weigh-station scales check against on the Interstate system:
| Axle Group | Federal Limit | What It Covers |
|---|---|---|
| Steer axle | ~12,000-14,000 lbs (tire-limited) | No federal number; capped by tire rating and state law |
| Single axle | 20,000 lbs | Any one axle, or axles spaced over 96 in. apart |
| Drive tandem | 34,000 lbs | Two rear tractor axles, 40-96 in. spacing |
| Trailer tandem | 34,000 lbs | Two rear trailer axles, 40-96 in. spacing |
| Gross vehicle weight | 80,000 lbs | Total of all axles, subject to the bridge formula |
A common rookie mistake is loading to 80,000 lbs gross and assuming that makes you legal. It does not. You can sit at 79,500 lbs gross and still get a ticket if your drives read 35,200 lbs. Always check each axle group on a CAT scale before you hit the highway.
Sliding Tandems to Redistribute Weight
Sliding tandems is the most common method for fixing axle weight imbalances. When your drive tandems are overweight, slide the trailer tandems forward — this shifts weight from the drives to the trailer axles. When trailer tandems are overweight, slide them back to shift weight to the drives. For the full step-by-step on direction, distance, and reweighing, see our dedicated sliding tandems weight distribution guide.
The rule of thumb: each hole position (approximately 2 inches) moves 250-500 lbs between axle groups, depending on the load. On a fully loaded trailer, one full slider position change can move 300-400 lbs. After sliding, always reweigh to confirm the adjustment worked. Do not guess — a precise calculation keeps you compliant.
Tire Rating vs Axle Rating
Bridge Formula and Axle Spacing
The bridge formula adds another dimension to axle weight compliance. Even if each individual axle group is within limits, the combined weight on a span of axles may exceed what the bridge formula allows based on their spacing. This is most commonly an issue when the distance between your drive tandems and trailer tandems is short — either because the trailer tandems are slid all the way forward or because you are running a shorter trailer.
For a standard 53-foot trailer with tandems at the rear, bridge formula compliance is rarely an issue. But for 48-foot trailers, specialized equipment, or configurations with tandems moved significantly forward, you should calculate bridge formula compliance using the weight regulations guide as reference.
Common Overweight Scenarios and Quick Fixes
Common Axle-Weight Mistakes to Avoid
State Variations on Axle Limits
While federal limits are the baseline, some states enforce stricter limits on state roads. Spring thaw restrictions can temporarily reduce axle limits to protect softened roadways. Some states enforce lower steer axle limits than tire ratings would allow. And certain bridge-posted limits override all standard calculations — if a bridge is posted at 40,000 lbs, no permit or axle configuration lets you exceed that.
Before running heavy through any state, check both the state weight limits and any seasonal restrictions. The cost of a quick phone call to a state DOT office is nothing compared to an overweight fine — or worse, damage to a weight-restricted bridge that results in criminal liability. For habits that keep you legal load after load, read how to avoid running overweight.
Axle Weight Limits FAQ
Common questions about axle weight limits for trucks
What is the steer axle weight limit?
There is no single federal steer axle limit, but tire manufacturer ratings typically cap it at 12,000-14,000 lbs. Most steer tires are rated for 6,150 lbs each (12,300 lbs total for two tires). Many states enforce steer axle limits in the 12,000-14,000 lb range. Exceeding steer axle ratings dramatically increases front tire blowout risk.
What is the tandem axle weight limit?
The federal tandem axle weight limit is 34,000 lbs. A tandem is defined as two consecutive axles with centers spaced 40 to 96 inches apart. This applies to both drive tandems and trailer tandems. Each individual axle within a tandem is limited to 20,000 lbs under the single axle rule, but in practice they share the 34,000 lb combined limit.
How do sliding tandems redistribute weight?
Sliding trailer tandems forward shifts weight from the trailer tandems to the drive tandems. Sliding them backward shifts weight from the drives to the trailer tandems. Each hole (about 2 inches) moves approximately 250-500 lbs between the two axle groups. This is the primary tool for balancing axle weights after loading.
Can I be overweight on an axle but legal on total weight?
Yes. This is one of the most common weight violations. Your total gross weight can be well under 80,000 lbs, but if your drives are at 35,000 lbs (over the 34,000 lb tandem limit), you will be cited. Axle weights and total weight are independent checks. Both must be within limits to be compliant.
What is the single axle weight limit?
The federal single axle weight limit is 20,000 lbs. A single axle is one axle, or a group of axles whose centers are spaced more than 96 inches apart. This is why each individual axle inside a tandem is technically capped at 20,000 lbs even though the tandem as a pair is limited to 34,000 lbs. Lift axles and spread configurations are usually judged under the single axle rule.
How do you fix an overweight steer axle?
Slide the fifth wheel rearward to shift weight off the steers and onto the drive tandems. Each notch typically moves a few hundred pounds. You can also shift cargo toward the rear of the trailer if it is loose freight. Steer axles run heavy when the load is too far forward or when the fifth wheel sits too far forward, so reweigh on a CAT scale after any adjustment to confirm you are under your tire rating.
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