California's main speed rule is the Basic Speed Law. You may never drive faster than is safe for the conditions, even below the posted limit. The handbook also sets fixed limits: 65 mph on most highways, 25 mph in school zones and residential areas, and 15 mph in alleys and blind intersections.
What is California's Basic Speed Law?
The Basic Speed Law means the safe speed depends on conditions, not only on the sign. In the handbook's words, "you may never drive faster than is safe" for the conditions. So a driver going exactly the limit in fog or heavy traffic can still be breaking the law.
The handbook lists what should set your speed, "regardless of the posted speed limit" on the sign.
- How many vehicles are on the road, and how fast they are going.
- The road surface: smooth, rough, gravel, wet, dry, wide or narrow.
- Bicyclists or pedestrians on or crossing the road.
- Weather: rain, fog, snow, wind or dust.
The DMV's own sample knowledge tests ask about this idea in more than one form. One asks what the Basic Speed Law requires. Another asks if you can get a speeding ticket while driving the limit. The answer is yes, when road or weather conditions call for a slower speed.
What are the speed limits in California?
Unless a sign says otherwise, the handbook gives these limits. Each one is a maximum, and the Basic Speed Law can still require you to go slower.
| Where | Limit | When it applies |
|---|---|---|
| Most California highways | 65 mph | "Unless otherwise posted" |
| Two-lane undivided highway | 55 mph | Unless posted otherwise; also the limit for vehicles towing trailers |
| School zone | 25 mph | Within 500 feet of a school while children are outside or crossing the street; some school zones are as low as 15 mph |
| Business or residential district | 25 mph | "Unless otherwise posted" |
| Blind intersection | 15 mph | The handbook calls an intersection blind when it has no stop signs at any corner; if your view is blocked, creep forward until you can see |
| Railroad crossing | 15 mph | Within 100 feet of the crossing when you cannot see the tracks for 400 feet in both directions; not if gates, a warning signal or a flagman control it |
| Alley | 15 mph | Any road no wider than 25 feet used to reach the back or side of buildings |
The railroad row shows up on the DMV's sample tests. Learn the three numbers together: 15 mph, 100 feet and 400 feet. For a closer look at crossings and school buses, see our school's guide to school buses and railroad crossings (opens in a new tab).
How much should you slow down in bad weather?
The handbook gives exact numbers for slippery roads and low visibility. They are the clearest examples of the Basic Speed Law at work.
| Condition | What the handbook says |
|---|---|
| Wet road | Reduce your speed by 5 to 10 mph |
| Packed snow | Reduce your speed by half |
| Ice | No more than 5 mph |
| You cannot see farther than 100 feet | Not safe to drive faster than 30 mph |
Rain is most slippery when it first starts, the handbook says, especially after a long dry, hot spell. For night, fog and rain practice, see fog, rain and night driving (opens in a new tab).
Can you get a ticket for driving too slowly?
Yes. Driving so slowly that you block normal traffic is against the law. Vehicle Code 22400 bans driving so slowly that you "impede or block the normal and reasonable movement of traffic." The exception is when the slower speed is needed for safety, because of a grade, or by law.
- If you choose to drive slower than other traffic, use the right lane.
- If a driver close behind you wants to go faster, move to the right.
- In heavy traffic or bad weather you must slow down. Still, the handbook warns that going faster or slower than the limit can get you cited.
How do speed and following distance work together?
The faster you go, the more room you need to stop, so speed and following distance are one decision. The handbook tells drivers to use the three-second rule and to scan the road at least 10 seconds ahead. It also says a passenger vehicle at 55 mph can stop within 300 feet. A large truck at the same speed can take up to 400 feet.
That gap is why cutting in front of a truck and slowing down is so dangerous. If a car merges too close in front of you, the handbook says to take your foot off the accelerator to rebuild space. Give more than three seconds on wet roads, behind motorcycles on metal or gravel, and when someone is tailgating you.
Quick answers
Check yourself
Sources
- California Driver's Handbook, Section 8: Safe Driving (Continued), Manage Your Speed (opens in a new tab)
- California Driver's Handbook, Section 7: Laws and Rules of the Road (Continued) (opens in a new tab)
- California Driver's Handbook, Section 8: Safe Driving (opens in a new tab)
- California Vehicle Code 22400 (minimum speed) (opens in a new tab)
- California DMV: Driving Performance Evaluation scoring criteria (opens in a new tab)
- California DMV: Sample driver's license knowledge tests (opens in a new tab)
Checked: October 5, 2026. Rules and forms can change; recheck the official page before acting.
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