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Tire Settings
Posted: Fri Oct 13, 2017 7:25 pm
by recampbelljr
I'm just setting this up, so I may be making a simple mistake.
When I go to insert my tire codes, it doesn't seem to have an option for the tires I'm running. (I'm running Dunlop Racing tires -- 450L15 in the front, and 500L15 in the rear.
Is there a way to insert these sizes?
https://flic.kr/p/Y1Mxv1
Re: Tire Settings
Posted: Sun Oct 15, 2017 9:16 am
by Harry
Good point
Racing tires often use manufacturer specific codings. I'm not deep in that topic, but the result is you need to convert the dimensions to the road tier notation standardized and used within LapTimer. This is a sample from wikipedia
When referring to the purely geometrical data, a shortened form of the full notation is used. To take a common example, 195/55R16 would mean that the nominal width of the tire is approximately 195 mm at the widest point, the height of the side-wall of the tire is 55% of the width (107 mm in this example) and that the tire fits 16-inch-diameter (410 mm) wheels. The code gives a direct calculation of the theoretical diameter of the tire. For a size shown as "T/A_W" use (2×T×A/100) + (W×25.4) for a result in millimeters or (T*A/1270)+ W for a result in inches. Take the common example used above; (2×195×55/100)+(16×25.4) = 621 mm or (195×55/1270)+16 = 24.44 inches.
So you need to either investigate how your tire's coding works or just measure dimensions T, A and W and use these in LapTimer. A is derived by measuring the height of the side wall S and make A = S/T*100. The letter for speed rating is not relevant for LapTimer, set it to any value.
- Harry
Re: Tire Settings
Posted: Mon Oct 16, 2017 11:46 am
by Mateusz
And just to clarify, if I am using a bigger or smaller than stock tire, what will entering the right info in the vehicle config change? Do I still need to enter the OBD wheel speed multiplier?
I guess there could be a flashing warning when speed exceeds tire rating - that's for autobahn driving on H-rated winter tires on the way to the Ring...
Re: Tire Settings
Posted: Thu Oct 19, 2017 11:16 am
by Harry
Changing the wheel size will change OBD speed values. So in case you are calibrating OBD speeds manually (Speed Multiplier), you need to adjust these when changing wheels. That's the same when tires wear off by the way... I may add an automatic calibration in the future
NB: Tire size is used for gear calculation and car visualizations (iOS) only.