Tyre size help

[Cruz]

I've seen a set of merc alloys with 205/60/15 tyres on.

The tyre calculator says that the diff percentage will be -4.13% and the physical -27mm

What does this mean exactly?

[CovKid]

Relates to speedo accuracy really. I too run Merc wheels (195/60/15's) and if I put them on top of an original wheel, the difference is slight - hence the % I guess. Not had chance to fully test how far out the speedo is but I seem to be about right at crucial speeds such as 30, 40 etc judging by the speed of other traffic and speed readers. I've actually got enough room (springs are high) to run 80s rather than 60s but these seem to be sigfnificantly more expensive so staying with what I've got, plus speedo is closer.

[Cruz]

So my speedo would then show me going slower than I actually am?

At the moment my speedo shows me going faster than my satnav says

[CovKid]

You may find the 205s a bit heavy on steering when parking but depending on the offset of the wheels, 15" merc wheels can transform the handling. 25 offset works for me (and still after a spare 126-400-2802 if anyone has one!)and wheels sit just inside arches. Do remember though, that the taper on merc wheel bolts is vastly different to VW so you need the right nuts/bolts to put em on with. I also found I had to remove the two brake drum retaining bolts but that was a minor trifle. I don't think you'll really notice much difference on the speedo - not enough to worry about. Speed cameras are actually useful at times as the speed of other traffic through those gives you some idea if your reading is out or not as most drive 'just' under the set limit. You may actually find the speedo is suddenly spot on!

Is it just me or do 14" wheels look ridiculously small on a T25??

[Cruz]

Seen a set of merc 16" rims with 4 good 225/55/16 95V load rated tyres

Would these be any good for running on the van? I know the running size if bob on but what about the load rating and steering?