How to change vehicle water spray in rain

Try vfxvehicleinfo.ymt It can now be opened & extracted using OpenIV (Ctrl+S when file is highlighted in OpenIV or right-click the file & select 'Extract to META/XML (.xml)').

There are 2 locations for the file:

\mods\update\update.rpf\x64\data\effects\vfxvehicleinfo.ymt

\mods\x64a.rpf\data\effects\vfxvehicleinfo.ymt

Note: You can search for 'vfxvehicleinfo.ymt' in OpenIV using Ctrl+F3 (Also 'Tools' tab> 'Search')

Edit the one in update.rpf (Only edit the one in x64a.rpf if you do NOT have one in update.rpf).

Note: When putting the edited file back using OpenIV don't change the '.ymt.xml' file extension just drag & drop it as is & OpenIV will convert it to a .ymt on it's own 👍

In 'vfxvehicleinfo.ymt' there are various item types. You will be mostly interested in:

There are others for forklift, golf car, motorbikes, trains, trucks etc

Under these headings (right at the very bottom of each) are these settings:

  <splashInPtFxEnabled value="true"/>
  <splashInPtFxRange value="100.00000000"/>
  <splashInPtFxName>water_splash_veh_in</splashInPtFxName>
  <splashInPtFxSizeEvoMax value="9.00000000"/>
  <splashInPtFxSpeedDownwardThresh value="2.00000000"/>
  <splashInPtFxSpeedLateralEvoMin value="2.00000000"/>
  <splashInPtFxSpeedLateralEvoMax value="18.00000000"/>
  <splashInPtFxSpeedDownwardEvoMin value="2.50000000"/>
  <splashInPtFxSpeedDownwardEvoMax value="18.00000000"/>
  <splashOutPtFxEnabled value="true"/>
  <splashOutPtFxRange value="50.00000000"/>
  <splashOutPtFxName>water_splash_veh_out</splashOutPtFxName>
  <splashOutPtFxSizeEvoMax value="9.00000000"/>
  <splashOutPtFxSpeedLateralEvoMin value="0.00000000"/>
  <splashOutPtFxSpeedLateralEvoMax value="2.00000000"/>
  <splashOutPtFxSpeedUpwardEvoMin value="0.00000000"/>
  <splashOutPtFxSpeedUpwardEvoMax value="2.00000000"/>
  <splashWadePtFxEnabled value="true"/>
  <splashWadePtFxRange value="50.00000000"/>
  <splashWadePtFxName>water_splash_veh_wade</splashWadePtFxName>
  <splashWadePtFxSizeEvoMax value="9.00000000"/>
  <splashWadePtFxSpeedVehicleEvoMin value="4.00000000"/>
  <splashWadePtFxSpeedVehicleEvoMax value="15.00000000"/>
  <splashWadePtFxSpeedRiverEvoMin value="0.00000000"/>
  <splashWadePtFxSpeedRiverEvoMax value="15.00000000"/>
  <splashTrailPtFxEnabled value="true"/>
  <splashTrailPtFxRange value="50.00000000"/>
  <splashTrailPtFxName>water_splash_veh_trail</splashTrailPtFxName>
  <splashTrailPtFxSizeEvoMax value="9.00000000"/>
  <splashTrailPtFxSpeedEvoMin value="0.50000000"/>
  <splashTrailPtFxSpeedEvoMax value="90.00000000"/>

I haven't edited any of them yet but I'm pretty sure this is what you are looking for. Make a backup of the original file before you start & you will then be free to mess about with the settings to see what each of them do in-game. Best of luck.