BustaWrench › Answers › How do I read iRacing telemetry?
The short answer
Four channels is enough: speed, throttle, brake, steering. Look for sharp edges where there should be smooth curves — a throttle trace that ramps gently out of a corner instead of snapping from 0 to 100, a brake trace that is a squeeze and a bleed instead of a spike. Then overlay a faster lap and find where their throttle comes up earlier. Ten minutes of looking beats ten laps of guessing.
Telemetry writes down what your hands and feet did, every lap. The trace is that diary drawn as a line graph — time along the bottom, channel value up the side. You do not need to be an engineer to read it. You need to know what a good line looks like.
Speed is your baseline: it tells you where you are gaining and losing. Throttle and brake are your pedals as 0–100% lines. Steering is your hands. That is four lines, and it is enough.
A good throttle trace is a gentle ramp up as you exit a corner. A cliff — throttle snapping from 0% to 100% — means you are stomping it, and the car will not thank you.
A good brake trace is a smooth squeeze to peak then a gradual release. A spike that looks like a lightning bolt means you braked too late and too hard, and you were probably sliding.
Steering is the sneaky one. A clean corner shows steady progressive turn-in then a smooth unwind. A sawtooth pattern means you are fighting the car, not driving it. And if the steering trace is flat while speed falls away, that is understeer — an entry-speed or setup problem, not a steering one.
Compare your trace to a faster lap. Load a ghost or a teammate's data and overlay it. Where does their throttle ramp up earlier? Where do they brake later but release more smoothly? That is your homework for the next session.
Do not analyse every channel. Just these four, and only for the corners you are losing time in.
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