# Tire Load Rating Calculations - In-Game Vs Reality

#1

I’ve begun to notice that the tire load ratings being calculated in-game are not really in line with tires in the real world, with Automation ending up quite a bit on the low side of things. I’ve knocked together a small spreadsheet to show some of the differences I’ve found:

Note that the calculated load rating does not change with the speed rating of the tire, nor the type of tire compound, or the quality slider either, for that matter - it is, as far as I can tell, solely a function of tire diameter and aspect ratio. And as you can see, low-profile tires, which are becoming far more common these days, seem to have a fairly significant discrepancy compared to higher-profile tires.

For example, the 235/75R15 tire, which was a fairly common light truck tire back in the 80s and 90s, has a rated load of 1984-2094 kilos per tire per the Automation calculation, vs 2039-2271 kilos per tire from real-world examples, which is about 90 percent of what the real-world tires can handle. The 295/35R19 tire, which is standard rear fitment on a Porsche 991, has a rated load of 1235-1433 kilos per tire in Automation, versus 1764-1984 kilos per tire in reality, effectively two-thirds of what a real-world tire can handle.

The effect of this is that it begins to punish cars that use lower-profile tires as part of their design, which doesn’t accurately reflect the direction that real-world manufacturers are going, for better or for worse.

Any thoughts on this issue would be appreciated!

#2

Is this all constant throughout the years too?

Same profile tyres could have different load rating depending on their ‘quality’, no?

Even if not, how close to the rl would you consider accurate enough?

#3

Yeah, it looks like it’s consistent year to year, which is pretty accurate to the real world - looking through the owner’s manual from a car now 20 years old, it gives the exact tore specification, right down to the load rating - which if you look the tire sizes up today, the load ratings remain the same. Also, changing between the different tire compounds makes no difference; this is pretty accurate in that an all-season tire of a particular size needs to deal with the same kind of loads as, say, a high-performance summer tire or even an R-compound tire. Quality makes no difference, and I’m not really sure it should in my mind - again, even the crappiest all-season tire will have broadly the same load rating as even the most expensive summer tire.

As for accuracy, I mean if real-world accuracy is possible then great, but if not, just closing the gap between tire profiles would be good enough.

#4

Thanks for looking into this, it is something I noticed too but have not had time to investigate and address yet.
This looks like there is a pretty simple solution. 5% extra load cap for high profile tires, 10% extra for low profile tires, lerp in between. That will make it accurate enough.
Cheers!