#1 and #3 would work. #2 would not. You could use with in place of in , but it introduces a possible ambiguity, that the tank trucks are being transported along with the liquids.
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lucas21c1. You can transport liquid goods by road in a tank truck.You can transport liquid goods by road in a tanker truck.
lucas21c3. You can transport liquid goods by road in tank trucks.You can transport liquid goods by road in tanker trucks.
lucas21cYou can transport liquid goods in a [tanker /tank truck].Tankers don't fly and they don't travel on water. The only way they can transport anything is by road. Therefore, "by road" is superfluous in this sentence.