CRG JUNIOR 100CC Guide de dépannage télécharger pdf (Page 23)

Tires (Care & Feeding)

Tire Pressures

The first thing that must be determined for a kart tire is correct inflation pressure, if you want to get the

best performance. That is easily said, but the real problem is the word “correct”, because its meaning

varies with conditions such as driver, frame, course layout, road surface, weather and temperature to

name a few variables. The manufacturer’s approved pressure is usually from around 10 to 18 psi.

The proper inflation pressure should be selected from that range to match individual conditions.

Lowering inflation pressure improves grip because the effective contact area of the tire is increased.

However, If pressure is lowered too far, contact becomes uneven and driving is more difficult.

Increasing inflation pressure generates heat faster and allows the tire to begin to grip sooner.

However, too much inflation pressure will distort the tire cross section, lift the tread and lose grip.

Try for pressures that do not increase more than 2-3 psi in a “race” length session. This is why careful

note taking is important. You must record the pressures before you drive a session (cold), then

immediately after returning to the pits (hot). Finding the correct balance between heat/grip/wear is the

key to success.

Start at 10 psi. Generally, when a tire is at approximately the correct inflation pressure, it will rise about

2 psi from cold to hot readings. Depending on the track layout, the four tires on your kart will build

pressure at different rates. Adjust each tire’s pressure up or down to hit that 2 psi rise. In other words,

if you go out at 10psi and when you return from your session, the right-rear tire is at 14 psi and the

right-front tire is now at 13 psi, you could drop that right-rear tire pressure 2 psi and the right-front

pressure 1 psi. The next time you go out on cold tires, reset the right-front pressure to 9 psi and the

right-rear pressure to 8 psi. Just remember the lower the cold pressure, the longer that tire will take to

“come in” and develop proper grip in that session.

Soft compound tires (cold) 8-9 psi

Medium compound tires (cold) 9-10 psi

Hard compound tires (cold) 12-13 psi

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CRG JUNIOR 100CC Guide de dépannage Page 23