Re: 4x108 rims/tires avail (long explanation of tire size)

[BRIT4VWS@aol.com]

Funny I was just calculating this the other day.  The correct sizes for my 
4000 are listed on my tire door as 195/60R14.  The total running Diameter is 
figured by this math formula W x.S  = H x 2= H2 + D = T.   In other words you 
can find the total 
                25.4
running diameter for your tires and then find the correct size for other 
wheels.  Lets figure it out.  Width is 195 and Section Height is 60 and wheel 
diameter is 14" we have two metric readings and one US reading so we have to 
convert all this to one or the other.  You take 195 multiply it by .60 that 
number comes out to be 117 and divide that by 25.4 to convert it to inches 
and that number is 4.61 this number is the tires side wall height from the 
wheel rim.  Take that number multiply it by two because you tire is a circle 
and you have 9.21" add 14" to this number and you get 23.21" total rolling 
diameter for your tires and wheels.  The optional tires size for my car 
stated on the fuel door is 175/70R14.  This is the winter tire I am guess as 
I can only find winter tires in this size.  This tire's total running 
diameter is 23.65" With this in mind my guess would be you could have any 
tire with a total running diameter of 23.2 to 23.65 and be fine on clearance. 
 Using reverse math you can subtract the wheel size from 23.2 and divide the 
number by two to get your side wall height and multiply that by 25.4.  From 
there you have a number of options as you could plug in a tire size such as 
215 by dividing with 215 you can get the sidewalls aspect ratio number in 
this case with a 15" wheel would be 51 and sense 51 does not exist you would 
go with a 215/50R15 plug this back into our original formula and your running 
diameter is a nice 23.46.  Sounds like a good size to me.  You can do this 
with all tires though my consensus is that these sizes will work in 15" 
wheels on my 87 4000 quattro.  195/55R15, 215/50R15, and a 205/55R15 would 
work but your talking about pushing it.  Smaller widths you could do a 
185/60R15 but again you would be pushing it a 175/60R15 would be excellent if 
they actually make one and I imagine this only being a snow tire.  I never 
calculated 16" out cause I never want to put that much more up-sprung weight 
on my car.

Britton Ingraham

87 4000 CS quattro
85 Quantum GL5
73 Beetle

LOOKING FOR!  88-87 Volkswagen Quantum GL5 5 speed.  Need not run but must 
have great looking body and interior that means NO RUST!  All colors are good 
but would prefer not to have Tornado Red the other lighter red is Awesome 
though and silver is really good!