iRacing's new Nationwide car with new tyre model now available

[Kevin Watts]

This highly anticipated update has now been released on the iRacing members site. The update includes numerous fixes and updates but the one most iRacing fans have been waiting for is the new tyre model preview that is being rolled out with the new NASCAR Nationwide model. The new tyre model has been worked on by David Kaemmer and his team for over a year and they believe that this new model is extremely authentic and will improve the feeling of being connected with the road surface and consider it may well be the most significant development in the iRacing service since it started in 2008. This new tyre model will eventually be included on all cars in the iRacing v2.0 update touted for release in August 2011 but for now iRacing fans will be able to put the new tyre and the new Nationwide car through its paces.

David Kaemmer had this to say about the new tyre model:

“Previous tire models for race simulations have been based on measuring real tires and fitting performance curves to data generated on test machines,” says Kaemmer. “But without understanding why tires generate the forces they do, it’s hard to predict what’s going to happen outside of the performance envelope where tires are tested. It also is very time consuming to determine the many numbers needed to describe a tire using a fitted model like that.
“So we went back to first principles to figure out how to model a tire from basic measurements we can do without putting them on a tire test machine. How does the patch of rubber in contact with the road generate grip? How does that patch of rubber move across the road? How does it distort when you climb a curb or when the tire starts to slide?

“The theoretical model we’ve come up with does the right things. When a car slides to a stop it takes the right amount of time; burn-outs look and feel right . . . all kinds of behaviors we used to struggle to reproduce by fitting numbers now happen almost automatically. There are comparatively few numbers involved in describing a tire now, all of which are much more easily measured. That means we’re more accurately reproducing the ways in which tires behave, which, in turn, enables us to make a car’s performance extremely authentic.”

The full release notes for this update are as follows:

2011 Impala B

- The new B class Impala (Nascar Nationwide COT
car) is now available as an update to the older Nationwide car. They are
distributed together as a single package, so if you own the current Nationwide
car you will automatically get the new one in this update. If not, simply
purchase the Nationwide car and you will get both. The new car has an updated
aerodynamic model which more accurately reproduces the high speed response to
setup changes. The suspension geometry and some suspension elements are also
updated, giving more accurate response when running coil-bind setups as well as
conventional setups.

- The new Impala B car also has a new, more
accurate tire model. This is a preview version of the iRacing 2.0 tire model;
there are a few known issues (lack of tire smoke being the most visible), but
the tires' response is very close to what you will experience when the model is
complete. The heavy, high-speed Nascar oval cars work the tires very hard, so be
aware that overdriving the car, or pushing too hard, will be costly in terms of
laptime and tire life. That said, we think you will enjoy them!



Cars

- We have revised all cars for race ending
suspension damage. Previously every car would not be allowed to continue a race
if it suffered 100% damage to any corner's suspension, which could be very
frustrating because you could destroy your suspension and not realize it and
your race is over. Now, just about every car can always have it's suspension
repaired effectively enough to keep driving. The exceptions that can still have
a race ended for excessive suspension damage are the Dallara IndyCar and Lotus
79, but these cars can also have a small amount of damage repaired, while the
Williams FW31 can't have any suspension damage repaired at all.



Old Impala B

- Updated some fixed setups.



Tracks

- The new tire model is very susceptible to
sustaining mysterious unexpected amounts of damage from wall corners and seams.
We have made some improvements to many tracks to reduce the chance of having
these weird invisible collisions against certain spots in the walls at many
tracks, but there may still be spots against walls where you may find the 2011
Impala B blowing a wheel out unexpectedly. We'll be working on improving this by
the time we do a full release of the new tire model.



Charlotte

- Removed Lowes logos.



Okayama

- Add gained time checkpoints at Okayama to
prevent cutting of pit entrance apex.


Bug Fixes

-
Don't do any further tech inspections on a car once it has started a race.


- Fix bug where tech inspection could lock you out of your car if you
were in the garage when the warmup ends and the race begins

- Corrected
a bug in fixed setup races where you could cause the sim to load the last used
non-fixed setup.

- Make the fixed setup button show properly in garage.


- Only lock a car that is too damaged to continue in the pits if it
isn't moving while it passes through the pit stall.

- Must let pitstop
begin when car is unrepairable if there is a fast repair available.

-
Fixed a bug where the pit speed limiter would keep the throttle cut and cause a
stalled motor if locking up the drive wheels from braking hard.

- Fix
bug involving selecting cars to view which have leading zeroes in their number.

 

[Ramon van Rijn]

Updating Thanks for the release notes.

 

[Joe Hubbard]

Thanks Kevin!

"- Corrected a bug in fixed setup races where you could cause the sim to load the last used
non-fixed setup. "

This makes me wonder if this was why some people in the vette were sooo much faster than everyone else in the practice or race.

 

[Abdul Al-Amry]