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Bike Shop 3-5 / Week 04 / Wednesday
3/6
Week 04 · Wheels, Tires and Air

Wednesday

Read the sidewall
// What holds a tire up
⏱ about 15 min

Wednesday: Read the Sidewall

Rocket wants his bike tire extra firm. "More air is always better!" he says, grabbing the pump.

Raven kneels by the tire. "Wait. What do you notice on the side of the tire?"

Rocket squints. There are letters and numbers in the rubber.

Nova shines a small light on them. "Those numbers are a message," she says. "Who wrote it, and why?"

A message on the side

The side of a tire is called the sidewall.

The sidewall shows a safe range of air pressure for that tire.

The range has a lowest number and a highest number.

Bike tire pressure is often measured in PSI.

PSI stands for pounds per square inch.

The air pressure must stay inside the range. Never go above the top number.

The best pressure inside the range depends on the load, so a grown-up picks it.

A grown-up checks the pressure with a pressure gauge.

Your job is to find the numbers and read them out loud.

SIDEWALL SMARTS
  • Read the question.
  • Tap your answer.
Where is the safe pressure range shown?
Who uses the pressure gauge?
Was Rocket right that more air is always better?
What does the S in PSI stand for? Type one word.
WHY THIS EXERCISEPSI stands for pounds per square inch.

Practice gauge readings

These are made-up practice numbers, not a real tire.

Pretend the sidewall says 40 to 60 PSI.

A grown-up checks the tire three times on three days.

Day (made-up)Gauge reading (made-up)
Day A35 PSI
Day B50 PSI
Day C65 PSI
Made-up readingIs it inside 40 to 60 PSI?
Day A: 35 PSI?
Day B: 50 PSI?
Day C: 65 PSI?
WHY THIS EXERCISEDay A is too low. Day C is too high. Day B is inside.
What was the lowest made-up reading? Type the number.
Day A needs how many more PSI to reach the bottom of the range, 40?
Day C is how many PSI above the top of the range, 60?
READING A TIRE, STEP BY STEP
  • ?Watch a grown-up check it with the gauge.
  • ?Read the pressure range out loud.
  • ?Find the numbers on the sidewall.
  • ?A grown-up holds the bike still.
  • ?Check that the gauge reading is inside the range.
WHY THIS EXERCISEHold, find, read, measure, then compare.

Look for damage too

While you look at the sidewall, check the tire for damage.

Look for cuts or bulges.

Look for anything stuck in the tire.

If you see something, tell a grown-up. Do not pull it out.

Safety first
Look and point only. A grown-up holds the bike still.
Keep hands away from the spokes.
No bike? Look at a picture of a tire, or a ball with printing on it.

Excellent detective work! Tomorrow we try a quick press test and see why air helps a bike roll.

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