Resistance usually affects performance when it is greater than 5% of the speaker’s impedance. There are two key aspects that affect the resistance of wires: the wire length and the wire’s cross-sectional area. Shorter wires have lower resistance. Wire lengths should be kept to a minimum but still separated. Also, ensure both speakers have similar wire length for equal impedance.
Wire thickness or gauge, is the cross sectional area of the wire. Resistance is less with thicker wire or a lower gauge. Resistance is therefore a combination of speaker impedance, length and gauge.