I found this while searching too, its on an old post from here.
1. Here's what the folks at 'Achtung Panzer' have to say about it:
"In 1941, OKH ordered that vehicles in and destined for North Africa were to be painted in yellow brown/sand yellow (RAL 8000) as a base colour with grey green (RAL 7008) for camouflage patterns. Yellow brown was to be used to cover 75% of the vehicle and grey green the rest. In the field, vehicles were often applied with mud and even captured British paints (such is war).
In addition, starting in spring of 1942, vehicles used in the southern parts of Russia, were often applied with tropical camouflage, similar or identical to those used in North Africa. In March of 1942, both colours used in North Africa were replaced by brown (dark sand) (RAL 8020) and dark (panzer) grey (RAL 7021). Brown was to be used to cover 75% of the vehicle and dark grey the rest...
In February of 1943, by the order of OKH, dark grey was replaced by dark yellow (RAL 7028) as the base colour for all German vehicles."
2. From the Squadron "Tiger In Action" book, Armor #27, pg. 17:
"The Tigers of sPzAbt 501, which depolyed to Africa in late 1942, were camoflaged in Desert Brown (RAL8020). Dark Gray (RAL 7027) was authorized to be used as a second color in a disruptive camoflage pattern, but there is no evidence that sPzAbt 501 ever painted their vehicles in this manner.
In the more temperate climates of coastal Tunisia, many of the tanks of sPzAbt 501 were overpsprayed with Olive Green (RAL 7008) to enhance their camouflage...
It is not known if any Tigers went to N. Africa painted in Dark Yellow (RAL 7028, also known as Wehrmacht Olive), which was specified for use as an overall basecoat on all combat and front line support vehicles during 1943 (in March, according to the first reference)."
SO, it seems that at least two references jibe on the base color, RAL 8020. Also noted are the Dark Gray (RAL 7027) and Olive Green (RAL 7008) counter colors, although the Tigers of sPzAbt 501 seemed to only use the green.
The back cover of the Squadron book shows a sPzAbt 501 Tiger in what I would call a true tan, as opposed to the more familiar Dark Yellow (RAL 7028). It also has the olive green counter shade.