Early look at iRacing 2021 Season 4 build updates

Justin Melillo
Beginner's Guide to iRacing: Where to even start?

The upcoming iRacing build is due at some point in the next week or two as 2021 Season 3 winds to a close. On the iRacing YouTube channel, a handful of videos were uploaded highlighting some of the upcoming changes for 2021 Season 4.

A lot of the “Season Spotlight” videos are focused on iRacing road license content. There are some updates coming to the AI and some NASCAR content as well. Check out the embedded videos below and read up on what’s in store for the next build.


Both the NASCAR Xfinity Series Class B cars and the NASCAR Camping World Truck Series Class C trucks will be getting a NEXT Gen upgrade in the shock department.

The NASCAR Cup Series NEXT Gen vehicle shocks will be utilized in part for these existing race cars and race trucks. The video states that the NEXT Gen uses a six-way adjustable shock, but Class B cars will utilize five-way and Class C will utilize four-way. The video also links to a new Shock Tuning User Guide which teaches how to properly adjust these virtual shocks.

The previous shocks installed were only two-way shocks. The video also drops information that the road course tire will be updated for all NASCAR vehicles. That includes the Class A NASCAR Cup Series and the NASCAR NEXT Gen cars. More information on both changes can be heard by listening to the video above.


Australian race fans, be advised that both the Holden and Ford Supercars are coming to iRacing AI. On top of that, Bathurst, Phillip Island and Oran Park will be included on the AI track roster.

For short track fans, the new Super Late Model is coming to iRacing AI as well. Five Flags and Bristol Motor Speedway will join the track roster.

In general, the AI cars across the service that were already included will be updated and will hopefully lead to a better experience.


All cars in the GT3 class on iRacing are getting a tire update and general improvements in the next build. Cars will be given better BoP parameters refinements amongst each other as well.

The tires in particular will be optimized for high speed, high load cornering for more confidence in holding higher speeds. They also won’t be fastest on the first lap anymore, but will optimize after a few laps around the track. Be careful on cold tires. Tires will degrade and stabilize as well.

Some cars will individually get chassis updates, some cars will individually get traction control optimization, and all cars in class will receive anti-lock brakes updates to coincide with the new tires.


The current model of IndyCar racing, the Dallara IR-18 will be getting a road tire model update that’s been influenced by real IndyCar driver feedback.

Specifically, the car can be driven more aggressively and off of the rear tires more without the fear of always going around. The Red and Black tire options will be updated to provide better strategy during race events. Setups included by iRacing will also be updated to be more competitive.


For the Lotus 49, both road and oval tires have been updated and will feature the latest iRacing tire technology. In general, the tires become more predictable on this car and are easier to understand, per the video. It is hoped that this car will still provide a challenge to users while the learning curve is lessened.

Tech Inspection ranges for the chassis have been updated to the realistic limits set in the 1967 and 1968 racing period. The driver adjustable anti-roll bars have been removed. Camber, air pressure and ARB ranges are now period accurate. Track-specific baseline setups will also be included for tracks accurate to this car’s period of racing.


Just like the 49, the Lotus 79 will update the oval and road tires in the next build. These updates will improve how the car drives around the edge of control, both above and below that threshold. Top speed will increase while corner speed will decrease. You can lean on the rear tires a little better in this build as well.

Previous setups will be at a point where they may not pass tech inspection anymore, but a bunch of baselines will be included by iRacing.


The Ford Mustang FR500S, Pontiac Solstice and Kia Optima, three of the road cars used in the Class D official series, will be getting updates in the Season 4 build. These changes are for use in the Sim Lab Production Car Challenge Series and Fanatec Global Challenge.

The Mustang is getting tire parameter updates. Cold tires will be more forgiving and will get to the right temperature sooner. Brake bias for this car is also getting adjusted, extending rearward.

The Solstice tire parameters are changing where it will be a racing tire on the car from now on instead of a street tire, per the video.

The Optima’s tire will be more balanced and will include more proper performance in the future build. Lap time fall off will be lessened. This car will also extend brake bias rearward.


On top of this, we know about the new Porsche that is on its way in the upcoming build. When we learn more, keep it pinned to Traxion for all of the latest iRacing news.

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