A Scania with steel suspension tag axle were 2.8 mtr wheelbase. They changed to 2.9 when they were Air suspended.
The Volvo S ride was a 3 mtr wheelbase normally. My friend had a left ■■■■■■ Air S ride that had a wheelbase of 3.2mtr.
http://www.euro-wheels.com/gallery/GB0711/imgpages/image038.html 3.2 Air
D541 ORO Tooleys | S2ley | Flickr 3.0 Steel
This is the up to date sheet from Volvo
http://productinfo.vtc.volvo.se/files/pdf/modelrange/fh62tb3hh1_gbr_eng.pdf
It may well have been a special Irvine build for other reasons than wheelbase, for example, as it was a tanker it may have had PTO requirements that dictated a special build, or had to conform to UK Petroleum Regs!
There is no AIR S ride , S ride is steel springs only
I ran an S ride for 6 or 7 years, the drive axle was on leaf springs and the tag axle was lifted and lowered by a single airbag. Hope this helps. macg.
Lilladan:
There is noAIRS ride , S ride is steel springs only
Yep although it had springs it was operated by air and not the old electric / hydraulic version from earlier. I never said it was on air suspension in my earlier post 
The S ride uses two steel springs , (one each side of chassis) both drive and tag are on these springs wid the long end to tag so that ten ton goes on to drive before any weight to tag , simple but very clever as usual wid Volvo , as some here say the lift was by a single air device in centrem av chassie , Scania was still using in the 1980s the logging bogie that Volvo designed in the 1940s !
think it was Ryds ,they did tags for bouth sweeds ,scanias vabis first 6 weelers from factory had drive on the third axle,cheers benkku
Volvo made thier own tag boggie efter they watch the Swedish drivers way to move 40 ton wid one drive axel , ans so as usual AB Scania-Vabis copied later , Volvo had taken some good engineers from Tadaholm
tidaholm was bought out by wallenberg and then it was a piece of the scania vabis group ,how many engineers went to volvo i don,t know but tools and buisnes did go to scania -vabis ,cheers benkku
Hey
I think you are looking for these 
As far as I know tag axles were only sold in Belgium with a single wheel from the second generation (1984) on.
Pusher and air ride were air suspended, s ride was steel suspension.
Pusher was, as a unit, available from the factory in 2 wheelbases, tag axle only in 3200 mm.
KH meaning without sleeper and LH was a sleeper cab
OK i found my United Kingdom spec sheets for Volvo tag axel tractors , S ride F10 WHEELBASE choice of 2.8 OR 3 M , F12 S ride 3 M , A ride F12 3.2 M , (all front to drive axel ) its been a while but it was as memorie gave me 
