What makes a Vanagon or Transporter syncro a 16"?
The 16" version differs from the 14" in a lot of details. To follow the flow of the manufacturing process we have to start with the bodywork. As the T3 Van has no seperate chassis-frame, additional reinforcements had to be integrated into the bodywork sheet-metal structure. This means thicker or more rigid material for the b-column, the shock-absorber flanges, suspension hinges. Gear-box and transmisions may differ from the 14" in their ratio according to the engine version in combination with options like high-roof etc. A rear diff-lock was included in the package, for some countries even the front diff-lock. There are e.g. also some special air tubes for the transmission and friction housing in order to avoid to sucking water while wading. The front suspension of the later models was changed from welded sheet-metal to a more rigid and corrosion-resistent steel-cast part, the CV-joints are covered by a special PUR protection shield. The rear half-axles have a bigger flange-diameter (108 instead of 100 mm). The filling of the visco-coupling is said to be slightly different in order to accelerate its traction control function. The 16'' package includes also enlarged brakes from the VW LT 3,5t light-truck - conventional drums at the rear, 280 mm disk-brakes in front. Factory tire size was 195 R 16, the 205 R 16 or 7.00 x 16 were also available with a new car, aftermarket suppliers enlarged the choice up to 31x10,5x16 or 245/75 R 16. Clearance between rear-suspension and the 16" tires seemed insufficient, so a modified suspension was designed, which also enlarged the wheelbase for another 20mm. More clearance is the reason for the modified wheel-wells. As the sheet-metal would otherwise interfere with the enlarged tires, the 'fenders' are modified and covered with these typical black extensions molded in polyurethane.
How can I figure out if a syncro is a stock 16"?
First of all it is not very likely to get in touch with one outside of Europe or the states around the Mediterranian Sea. Have a look at the numbers at the sticker near the fuse-box near the drivers-doors or in your service booklet. You will find one number starting with e.g. 253 for a Kombi based vehicle, 255 for a Caravelle or Vanagon GL (see also production figures above and the dictionary at vanagon.com) The three digit number that follows tells you about the stock engine, body, tire & rim combination. The first two digits are quite complicated to structure, the last one tells you factory tires for your model were 185 R 14 tyres if '7', 205 R 14 if '5' and finally 195 R 16 if 'A'. The optional 205 R 16 tires were encoded M 855.
taken from:
http://www.vanagon.com/syncros/syncro16/index.htm
