Tire Strategy
Dry Tires (Slicks)
Ultra Soft (Purple)
Very high speed, very low durability
Super Soft (Red)
High speed, low durability
Soft (Yellow)
Above average speed, below average durability
Medium (White)
Average speed, average durability
Hard (Orange)
Below average speed, best durability
Wet Tires (Grooved)
Intermediate (Green)
Used for little to moderate rain condition.
When wet level is within range alphabet "o" and just before "k" in the "water on track" text, the intermediate tyres work best, however just before "o" seem to give you little advantage over slick tyres.
Wet (Blue)
Only for heavy rain condition.
Wet tyres are not very often used and when it is used in an intermediate tyre range; the car performance is impacted very negatively.
The effective range of wet tyres are between "k" (k meaning just below alphabet "k" in "water on track" text) to the end of the gauge.
Fuel Strategy
(These numbers are a rough guide and have various modifiers which can and will affect the actual returns)
Super Overtake (Pink) - A level beyond that of Overtake, only available as a mechanic knowledge perk.
Overtake (Red) - Uses 1.5 Laps of fuel (per fuel gauge) for each driven lap
High (Orange) - Uses 1.25 Laps of fuel (per fuel gauge) for each driven lap
Medium (Yellow) - Uses 1.0 Lap of fuel (per fuel gauge) for each driven lap
Low (Blue) - Uses 0.85 Laps of fuel (per fuel gauge) for each driven lap
Fuel manufacturer chosen during pre-season car construction definitely affects fuel efficiency. There are certainly other less obvious things which also have an impact on fuel efficiency.