iRacing prototype & LMP racing: the discipline, the cars, the ladder
Prototypes are iRacing’s downforce school. Five official road series cover the ladder from a 700-kg Radical to the GTP hybrids, and every one races every 2 hours at :00 past the hour in UTC.
GT3 has a top-of-the-hour sprint to catch; prototypes do not. At a 2-hour gap, the session that lands in your evening depends entirely on your timezone, so each series page below converts the slots to your local time.
Where to start
Section titled “Where to start”Which prototype series to run comes down to two things: your road license, then your appetite for grip.
- Radical Esports Cup. Class B, running the Radical SR10, a spec, sequential-shift sports-prototype with modest downforce. It is the gentlest introduction to driving on aero. The single-car field means clean racecraft beats setup tinkering.
- LMP3 Trophy. Class B, running the Ligier JS P320, a closed-cockpit LMP3 with a Nissan V8. More downforce and more weight than the Radical, but still forgiving. Most drivers take this step before LMP2.
- LMP2 Challenge (Fixed). Class A, running the Dallara P217. The setup is fixed, so the race is decided on track rather than in the garage. This is genuine LMP2 pace and the cleanest single-class A-license prototype on the service.
- Prototype Challenge (Fixed). Class A, the GTP field: Porsche 963, Ferrari 499P, Cadillac V-Series.R, Acura ARX-06, and BMW M Hybrid V8. The hybrid system runs fully automatically as of 2025 Season 4, blending engine and electric power to a fixed output with no driver deployment control. Fixed setup, top-tier grip. Earn it.
- Proto-GT Challenge. Class A, the multiclass oddity: the HPD ARX-01c prototype shares the track with GT1/GT2 metal (Ford GT, Corvette C6.R, Aston DBR9). Run it to practice traffic management rather than raw prototype pace.
The mechanism behind the ladder is simple. Downforce rewards commitment and punishes lift-off mid-corner, so the lighter cars teach you to trust the floor before the GTP cars demand it.
The prototype series
Section titled “The prototype series”Because all five run on a 2-hour cadence, no slot is ever “always next.” The per-series pages above already convert every upcoming session to your local time for free. If you would rather have the next green flag in your timezone pushed to your wrist instead of doing the UTC math, that is what Startlight ($9.99, iOS / Home Screen widget / Apple Watch) does.
New to road racing on iRacing? Read Getting started for the license and Safety Rating basics, or browse every iRacing series.
Frequently asked questions
Which iRacing prototype series should I start with?
Start with the Radical Esports Cup (Class B, Radical SR10) or the LMP3 Trophy (Class B, Ligier JS P320). Both are light, fixed-setup-friendly entry points into downforce racing. Move to the LMP2 Challenge (Dallara P217) and the GTP-spec Prototype Challenge once you hold a Class A road license.
How often do iRacing prototype series race?
All five core prototype series run every 2 hours, at :00 past the hour in UTC. Because the gap is over an hour, the slot that lands in your evening depends on your timezone. Each series page converts every upcoming slot to your local time.