These two are the essential parts for speed limit modding:

1. Extract all country folders stored under "/def/country/" folder in game asset def.scs file. Each country folder contain "speed_limits.sii" file. They full qualified path will be look like this:
   
   /def/country/albania/speed_limits.sii /def/country/austria/speed_limits.sii /def/country/belgium/speed_limits.sii /def/country/bosnia/speed_limits.sii : : etc
   Edit this "speed_limits.sii" file (using Windows Notepad or other Text Editor app) and change the speed limit for cars, trucks, and buses (sometimes also trains and trams) to what you need. This part is a global default speed limit specific for each country. Any region in the map that has no specific speed limit will fall back into this global default values.
   
2. Speed limit for specific purposes and regions are declared in "/def/world/traffic_rules.sii" file. Open it with any Text Editor app and change to what you need. In this file, speed limit segments has a value "speed_limit" in their rule attribute. Here an example of segment that declare speed limit 50 KPH:
   
   traffic_rule_data : traffic_rule.limit_50 // <-- this is segment name { # name: "[speed] Speed limit 50" // <-- this is rule name (unused) rule: "speed_limit" // <-- rule attribute for speed limit definition num_params[]: 50 // <-- value for speed limit definition (in KPH) }
   This part is for specific speed limit for perticular region, area, etc. They are not based on specific country.

Before modify this speed limit, you must understand the basic modding for ETS2 (and ATS too). If you know nothing about modding before, search the internet for tutorials and tips.

Thanks for the explanation. I've been trying to find this from scs forum and google but can't find anything

If you find problem in any part of this speed limit modding, don't hesitate to ask. Happy modding.

I extracted the def.scs file with the scs extractor program as you said, but there are no .sii files in the country file

引用自 ichbinumut：

I extracted the def.scs file with the scs extractor program as you said, but there are no .sii files in the country file

Not in the country file, but in the country folder. Here the file structure of country folder in Explorer after extracting the def.scs asset file:

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3503613530

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3503614053

If you can't find "/def/country" folder path after extracting the def.scs file, you probably using an older version of SCS Extractor or using wrong def.scs file.

The def.scs game asset file is located in game installation folder, typically stored under "C:\Program Files (x86)\Steam\steamapps\common\Euro Truck Simulator 2\" folder.

Madman, if you could give me your Discord address, I have a few questions for you.

引用自 ichbinumut：

Madman, if you could give me your Discord address, I have a few questions for you.

Sorry, I'm not using Discord anymore.