Greater speed influence, head or tail wind

[wobblywalrus]

Aero drag is exponential.  Adding 10 mph to the air speed creates a greater change in drag than the subtraction of 10 mph, as an example.

[Truckedup]

As it happens Bonneville Pro has a sample bike data that just about match your question. No wind, 130.7. 10mph head wind, 125.5. 10 mph tailwind, 136. FWIW

  Yes, the exact situation...The class I run the bike in just had the record raised by 4 mph....Guys at that track said there was a tail wind that day...Of course I don't know if it was blowing when the bike was running and might just be good tuning....

[jacksoni]

Well, whatever the physics are, I'd rather have a tail wind!!

[Truckedup]

Well, whatever the physics are, I'd rather have a tail wind!!

 If you race at Ohio or Maine a tail wind is a rare thing.....But when my bike is on the track it's a head wind and for my competitions it's always a tailwind....

[bbarn]

Correct but the variation in effect has more to do with individual vehicle shapes and the speed they are capable of.  At 350 mph, a headwind isn't going to matter as much as a vintage car running a top speed of 100 mph.  In other words, the loss isn't a percentage, so to quantify in simple terms is all but impossible other than to say a 10 mph head wind is going to have the same effect as the wind resistance of going 10 mph faster and vice versa - whatever effect that is in your situation.  In some cases it may be overcoming 20 hp, in other cases 100 hp or more based on vehicle speed and shape - not so much about a flat 1.5% variation of loss of by a head wind versus tail wind.   
Please correct me if I have this wrong. 

Exactly my point. There is an academic answer to the question and there is a practical answer to the question. I was shooting for the practical since the academic would require me to show my work and it has already been a LOOOOOOG week! 

[Sporty Dan]

For the Head wind versus Tail wind, isn't it just that there is a difference in the overall aero drag at speed? Say you have a 10 mph headwind, that would be in essence the aero drag of 210 mph wind when the vehicle was at 200 mph. The reverse would be the aero drag of 190 mph wind with a tail wind at 200 mph. So there would be a 20 mph aero drag swing between the head and tail winds. Based on that, I would think a head wind would have a greater influence as the speeds got higher.

[distributorguy]

For the Head wind versus Tail wind, isn't it just that there is a difference in the overall aero drag at speed? Say you have a 10 mph headwind, that would be in essence the aero drag of 210 mph wind when the vehicle was at 200 mph. The reverse would be the aero drag of 190 mph wind with a tail wind at 200 mph. So there would be a 20 mph aero drag swing between the head and tail winds. Based on that, I would think a head wind would have a greater influence as the speeds got higher.

Exactly.  But as stated earlier, its (relatively) exponential not a straight percentage.