How to Read a Telemetry Trace: A Sim Racer's Guide

What a telemetry trace actually is

A telemetry trace is a graph of one car input or state over time — or, more usefully, over distance around the track. The horizontal axis is the position on the lap; the vertical axis is the value of whatever the trace is measuring: throttle, brake, speed, steering angle, slip, tyre temperature, suspension travel.

On its own, a single trace tells you what you did. The real value comes from putting two traces side by side — your lap against a faster lap, your current run against your personal best — and looking at where they diverge. Every divergence is a place you might be gaining or losing time.

The four traces you'll use most

1. Speed

The speed trace is the simplest and the most honest: it's a direct readout of how fast the car is moving at every point on the track. When you compare your lap to a faster one, the gap between speed traces is literally the time gap, integrated over distance.

• Where your trace is lower than the reference: you're losing time. This is the headline.
• Where your minimum corner speed is lower: you're either braking too early, braking too hard, or carrying less mid-corner speed. Drill into the brake and throttle traces to find which.
• Where your top speed on a straight is lower: almost always a corner exit problem — you got back on the throttle later than the reference lap.

2. Throttle

The throttle trace shows what percentage of throttle you're applying at every point. It's the single most useful input trace for finding lap time, because the moment you go back to 100% throttle out of a corner is the moment lap time stops being lost and starts being gained.

• Look at the throttle-on point. If a faster lap is back to full throttle 30 metres earlier than yours, that's the gain — and it usually traces back to a better line or earlier rotation, not "being braver."
• Watch for lifts in the middle of corners. A dip from 100% to 80% mid-corner usually means the car got loose or you arrived too hot. The fix is upstream — a slower entry or a different line.
• Partial throttle on exit is a tuning or technique signal. If you can't take full throttle out of a corner, you're either overdriving it or the car isn't planted enough.

3. Brake

The brake trace shows brake pressure as a percentage. Most fast drivers' brake traces look the same: a sharp ramp up to maximum pressure, then a smooth release as the car turns in.

• The shape of the release matters more than the peak. A straight cliff off the brakes loads the front tyres suddenly and unsettles the car. A smooth trail-off keeps weight on the front and helps the car rotate.
• Compare brake-on points. If you're braking 10 metres earlier than the reference, you have free time waiting in that braking zone.
• Watch for re-applications. If your brake trace touches zero and then comes back, you under-braked the first time and had to correct. Usually a sign the entry speed was wrong.

4. Tyre slip (or wheel speed)

Slip is the difference between how fast the tyre is rotating and how fast the car is actually moving over the ground. Too much slip on the driven wheels under throttle means wheelspin. Too much slip on the front wheels under braking means lockup. Both cost time.

• Spikes under throttle = wheelspin. The car isn't accelerating as hard as it could be. Either you got on the throttle too early, too aggressively, or the car needs more rear grip from setup.
• Spikes under braking = lockup. The tyre stops rotating relative to the ground. You're not slowing down efficiently and you'll flat-spot the tyre.
• Sustained mid-corner slip = the limit of grip. A small amount of consistent slip on all four corners through a fast bend is exactly what a fast lap looks like. Zero slip means you have grip in reserve.

How to actually compare two laps

Pick your best lap as the reference and a recent representative lap as the comparison. Overlay the speed traces first. Find the biggest gap between them and zoom in on that section. That's where you'll spend the next ten minutes.

• Identify the corner. Use the track map to figure out which braking zone, apex, or exit the gap is at.
• Layer in throttle and brake. Did you brake earlier? Lift mid-corner? Get back to throttle later? One of these is almost always the answer.
• Check the slip trace. If you got off the throttle, was the car loose? If you braked harder, did you lock up? The slip trace explains the input choices.
• Form a single hypothesis. "I'm losing 0.2s at Turn 4 because I'm braking 10m too early and arriving slow." Then go drive that one corner.

Common mistakes when reading traces

Chasing the shape, not the cause

It's tempting to look at a fast lap's brake trace and try to make yours look identical. That's backwards. The fast lap's brake trace is a result of a better entry speed, a better line, and confidence in the car. Copy the cause, not the shape.

Comparing different conditions

Different tyre temps, different fuel loads, different weather — any of these will move the traces. If you're comparing a cold first lap to a warm Q lap, the differences aren't all driver-driven. Compare like for like.

Ignoring the steering trace

Steering input is one of the most underrated traces. Smooth, single-input steering is fast. Steering corrections — quick wiggles around the apex — mean the car got out of shape and you're catching it. Less steering input over the lap is almost always faster.

What changes once you can read traces

Most sim racers go faster by guessing. They guess they were braking too early, guess their line was wrong, guess they didn't get on the throttle in time. Reading telemetry replaces guessing with seeing. You stop trying to be braver and start finding the single, specific input change that costs no courage and gains a tenth.

That's the real shift: from "I think I'm slow at Turn 6" to "I'm 0.18s slower at Turn 6 because my throttle re-application is 25 metres later than my best lap, and the cause is an early apex." That second sentence is something you can actually fix.