Assymetric speaker cable lengths?

I'm setting up a system for a family member and the particulars of the room would require a 24 ft length of speaker cable to the right channel, but 10' would be enough for the left. This is a mid-fi tubed system.

Would it be OK to do this? I mean the signal travels at near the speed of light, so would it create a problem arriving at the left channel a nano-second (or less) sooner?

Many thanks
The audio signal travels @ slightly less than the speed of light (186,000 mi./sec). You'd need a difference of several 100 miles to hear any difference. As long as you're using 14 Ga. wire or better, you're fine. Also @ your lengths, resistance, capacitance & inductance will present no problems.
Speed is not the issue. For a tube setup, however, it can be quite sensitive to load. The slight difference is still unlikely to be audible but if you are driving low impedance speakers or speakers with a bumpy impedance curve then it is much safer to use teh same lengths.
Ah, that issue again! Here is something else to worry about.

The earth is rotating...moving East at about 700 mph at 45 deg lattitude. So, the speaker at the East side of your setup is moving away from signal while the one to the West is moving towards the signal. Thus the transit times of the signal will be different even if the wires are the same length. Furthermore the Dopler effect will cause frequency differences. The obsessive audiophile will therefore set up his speakers North and South.
The tube load theory doesn't hold water @ your lengths. Low impedence spkrs. w/ a bumpy impedence curve (>90% of the spkrs. on the mkt have less than ideal impedence curves) can be overcome by going w/ a heavier Ga. spkr. cable.
As Shadorne pointed out, impedance is the big issue here. Check out Townshend Audio's website; their Isolda Matched Impedance cable is supposed to tackle the issue (have never tried this myself though)