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Old September 6th 2008, 01:01
vwdevotee
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Ghia wheel fun.

Since what fits on a Ghia seems to be a bit of a black hole as far as information goes, I thought I would share some of my analysis on the subject.

I have a '73 Coupe, with 185/65R15 tires on 15x5.5 ET22 wheels, and I get just the slightest tire rub under a hard squat. So, with that in mind I think that this is the furthest out I would be comfortable having my tires. I used one long ruler across the sidewall bulge and another ruler to the spring plate; this measured 10 inches almost exactly. I also measured the distance from the mounting face of my '86 Turbo trailing arms (on the brake disc hat) to the spring plate, and found it to be 8 inches.

So, I am looking at 19x8 inch 997 Carrera wheels (shown below) and was playing with some numbers. These wheels have an offset of 57mm, and normal wear 235/35R19 tires. Just looking on TireRacks website, I found that most of the tires in this size have a section width of about 9.4~9.6 inches, when measured on an 8.5 inch wide wheel.

Now, with a 9.6 inch section width, and 57mm of offset, there is just over 7 inches of wheel/tire inboard of the mounting surface:

9.6/2+57/25.4=7.044 inches

The balance of the wheel/tire is outboard of the surface

9.6-7.044=2.556 inches

The inboard part of the tire is less than 8 inches, so no spacer is necessary at this point (the shock tower might change that), but, since there is only 2 inches available between the fender and the mounting face (10 from fender to spring plate - 8 from spring plate to mounting face), the fender will need to be flaired by 0.556 inches.



Now just for giggles, lets look at GT3 wheels, and see how bad things get. The current GT3 uses 19x12 ET 53 rear wheels (12.6 inch section width using 305/30R19 tires):

12.6/2+53/25.4=8.38 inches

Since this is further back than the spring plate a spacer will be needed to provide clearance (I'll go with 1.0 inch spacer to clear everything). Thus, the outboard part of the tire/wheel will be:

12.6-(8.38-1)=5.21 inches

Since there is a 2 inch allowance from mounting face to fender, the fender will need to be flared about 3.25 inches to allow clearance.


In the other hand, I've been told the 7 inch wide boxster wheels (typically 55mm offset) will bolt in without body mods, and according to a similar analysis the numbers I get agree. Using a nominal 8.2 inch section width the inboard side should be about 6.3 inches (no spacer, so I'm happy), and the outboard side of the wheel/tire should be 1.9 inches from the wheel mounting face. So, since it's less than my 2 inch allowance, everything should fit just as people have found.


Well, if anyone can poke holes in my arguement, then please let me know what I'm forgetting and I'll figure out how to include it.


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  #2  
Old July 25th 2009, 23:35
flat_iv flat_iv is offline
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Join Date: Feb 2004
Location: Nashville, TN, USA
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Its good to do a lot of measuring. I have a 74 Ghia with 16x6 1/2" wheels. Be carefull when picking out tires because they are not all created equally. For example a 205/45/16 tire can vary in width around 3/4" depending on the brand. Also with my front tires I have to use a topline sway bar because the factory sway bar rubbed. Also had to cut down the turning radius because the inner whel was rubbing. Also because a ghia doesnt have any type of flare to the fender you have to be carefull turning and going over a bump at the same time. I fixed my issues by dropped spindles and then adding 15% stiffer torsion bars in the front to raise it a little. I have no rubbing at all. The rear of the ghia has plenty of room.
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