Iowa CDL — General Knowledge practice
Iowa CDL — General Knowledge: Speed & Space Management practice test
Choosing a safe speed, keeping a space cushion, adjusting for weather and traffic, and understanding stopping distance.
Content reviewed against official driver handbooks · August 12, 2026
13 questions · pass with 10 correct. You get instant feedback and an explanation after every answer.
Study questions with answers
12 sample Speed & Space Management questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
Show all 12 questions with answers
1. In states where trucks and buses have lower speed limits than cars, how big can the difference be?
Correct answer: As much as 15 mph
Truck and bus limits can run as much as 15 mph below car limits, so take extra care when changing lanes or passing on those roads.
Source: Iowa Commercial Driver's License Manual — Section 2.6.5, Speed and Traffic Flow
2. What does selecting a low range on an automatic transmission do on a downgrade?
Correct answer: It keeps the transmission from shifting up past that gear, giving more engine braking
Lower ranges stop the transmission from upshifting beyond the selected gear (unless governed rpm is exceeded), which provides the engine braking you need on grades.
Source: Iowa Commercial Driver's License Manual — Section 2.3.3, Automatic Transmissions
3. Why do dry bulk tanks call for extra caution in curves and sharp turns?
Correct answer: They are top-heavy, and their contents can move around
Dry bulk tanks are top-heavy and their contents can shift, so take curves and sharp turns slowly and carefully.
Source: Iowa Commercial Driver's License Manual — Section 3.4.1, Dry Bulk
4. What can too little weight on the drive axles cause?
Correct answer: Poor traction, so the drive wheels spin easily
Without enough weight on the drive axles, traction suffers and the drive wheels may spin; in bad weather the vehicle might be unable to keep going.
Source: Iowa Commercial Driver's License Manual — Section 3.2.4, Balance the Weight
5. With less than a full load of livestock, what does the manual recommend?
Correct answer: Use false bulkheads to keep the animals bunched together
False bulkheads keep a partial load of livestock bunched. Even then the animals can lean in curves, shifting the center of gravity and raising rollover risk.
Source: Iowa Commercial Driver's License Manual — Section 3.4.3, Livestock
6. What's the advantage of slowing down and downshifting before you enter a curve?
Correct answer: You can apply some power through the curve for stability and accelerate as you exit
Getting into the right gear before the curve lets you use a little power to keep the vehicle stable while turning and speed up as soon as you're through.
Source: Iowa Commercial Driver's License Manual — Section 2.3.1, Manual Transmissions
7. How does overloading affect a truck on hills?
Correct answer: It must crawl up upgrades and may pick up too much speed on downgrades
An overloaded truck slows to a crawl when climbing and can pick up excessive speed when descending. It also needs more room to stop, and brakes pushed too hard can fail.
Source: Iowa Commercial Driver's License Manual — Section 3.2.2, Legal Weight Limits
8. In freezing weather, what does it suggest when the vehicles ahead of you stop throwing spray off the road?
Correct answer: Ice has formed on the road
A lack of spray from other vehicles is a sign that ice has formed. Also check your mirrors and wiper blades; if they're icing, the road probably is too.
Source: Iowa Commercial Driver's License Manual — Section 2.13.2, Driving
9. Why is hanging meat in a refrigerated trailer a tricky load?
Correct answer: It can be very unstable with a high center of gravity, so you must go slowly on sharp curves like ramps
Suspended beef, pork, or lamb makes a very unstable, top-heavy load, so take sharp curves such as on- and off-ramps slowly.
Source: Iowa Commercial Driver's License Manual — Section 3.4.2, Hanging Meat
10. When is a high center of gravity most dangerous?
Correct answer: In curves, or when you must swerve to avoid a hazard
Cargo piled high or heavy cargo on top makes tipping over more likely, especially in curves or a sudden swerve. Keep the load as low as possible.
Source: Iowa Commercial Driver's License Manual — Section 3.2.3, Don't Be Top-heavy
11. On an upgrade, which conditions make you rely more on lower gears to climb?
Correct answer: A steeper or longer grade and a heavier load
Gravity slows you on any upgrade. The steeper or longer the grade, or the heavier the load, the more you'll need lower gears to get up it.
Source: Iowa Commercial Driver's License Manual — Section 2.16, Mountain Driving
12. What can happen if too much weight is placed on the steering axle?
Correct answer: Hard steering and possible damage to the steering axle and tires
Overloading the steering axle makes steering hard and can damage the axle and tires. Balance the weight across the axles.
Source: Iowa Commercial Driver's License Manual — Section 3.2.4, Balance the Weight
More CDL — General Knowledge topics
Practice Speed & Space Management in another state
Every Iowa question is written from the official Iowa driver handbook and checked against its current edition. DMV Test Free is a free, independent study resource — not affiliated with any DMV or government agency. About DMV Test Free