Try to put units

assets/themes/maxspeed/maxspeed.json

@@ -139,6 +139,43 @@
         }
       },
 	  "allowSplit":true
+	  "units": {
+		  "appliesTo": ["maxspeed"]}
+    "applicableUnits": [
+    {
+"canonicalDenomination": "km/h",
+"alternativeDenomination": ["km/u", "kmh", "kph"]
+"default": true,
+"human": {
+"en": "kilometers/hour",
+"ca": "quilòmetres/hora",
+"es": "kilómetros/hora",
+"nl": "kilometers/uur"
+},
+"humanShort": {
+"en": "km/h",
+"ca": "km/h",
+"es": "km/h",
+"nl": "km/u"
+}
+},
+{
+"canonicalDenomination": "mph",
+"alternativeDenomination": ["m/u", "mh", "m/ph"]
+"default": false,
+"human": {
+"en": "miles/hour",
+"ca": "milles/hora",
+"es": "millas/hora",
+"nl": "miles/uur"
+},
+"humanShort": {
+"en": "mph",
+"ca": "mph",
+"es": "mph",
+"nl": "mph"
+}
+},
       "mapRendering": [
         {
           "icon": {