i’ve done a bunch of searching, but have not found a definitive answer. Does anyone know if the Gr4 wheels will fit on a factory 74’ GTS? I currently have the old Hall ultras on and have the origional Campys.
I have been considering putting the old Campys on but love the wider look. To me the Mavics gives the best of both. An old school factory correct look (at least on the Gr4 cars), with the width that fills out the fenders.
Picture for attention.
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The Group IV wheels are 10" front and either 13" or 14" rear depending on which rear rim you have (they made both). There is only one street legal tire available for this rim combo which is the Pirelli P7s which will cost you about $2800. for a set. I have 10 and 13" wide Gotti's on my car and they are under fiberglass Group IV flares (riveted on per the way the factory did). There is no way those rims would fit under a GTS flare. You also have to cut the sheetmetal as the tires stick out very far and will hit in the corners when turning the wheels. The Marvic rims are period correct in magnesium but you will have to cash in your 401K for a set. A much cheaper alternative is to buy a set of cast Roin Group IV rims which they make to spec from the original wheels. But again, you will have a wheel tire combo sticking out 4 " on the back and 3" in front. Kinda like a Dukes of Hazard thing. Hope it helps.
Appreciate the response but still a bit confused. I currently have 335s in the rears that seem to fit no problem. My understanding is the 14” x 15” would be a 345 which is 10mm (.4 inch) wider. Also, it looks like Mavic have custom offsets. So not sure how the rears would look 4” too wide in the rear given they are 1” wider than the current set up shown here?
You are correct wrt the tire size - 345/35-15. It's the offset of the rim. Mine are a 5.0" backspace which is pretty close to the Group IV factory rims. Not sure what your wheels are but they must have a deeper backspacing to tuck under a narrower body car. Try taking one of your rims off and position it with regard to the hub with a 5" backspace. Maybe its not 4" with your GTS flare but it will still be beyond the edge IMHO.
Drop a level from the edge of the flare and measure back to the hub flange. Marvic only make the 14" width rear (not the GT5 / GT5S 13") and they sit out to the edge of a GT5 / GT5S flare.
Marvic have technical documentation on their site with offsets.
Group 4 https://www.marvic.it/public/p...0-14x15_2016-eng.pdf
GTS 10" https://www.marvic.it/public/p...TS_8-10_x_15-eng.pdf
This thread may be of help, with photos of Marvic's 10" GTS rear wheel. https://pantera.infopop.cc/top...and-roin-information
Appreciate the input gentlemen. I need to figure out if they will do custom offsets. If they do, the second question,would be working to figure out what those offsets would need to be. Dropping the level off the fender lip and measuring back to the hub is probably the right first step!
Would love it if somebody had already figured it out as there is definitely room for error here.
I don't believe either Marvic or Roin will do "custom" offsets. They are both CAST wheels with fixed backspacing. Marvic specifically was commissioned to make these wheels to fill the void of original wheels being needed by the historic race community. Roin will make you a 3-piece wheel that would look pretty nice IMHO.
@panterapatt posted:I don't believe either Marvic or Roin will do "custom" offsets. They are both CAST wheels with fixed backspacing. Marvic specifically was commissioned to make these wheels to fill the void of original wheels being needed by the historic race community. Roin will make you a 3-piece wheel that would look pretty nice IMHO.
Well I have several rims from Roin. The Gt4 look alike rims are all cnc-machined and welded together of two pieces. Its easy to see if you try to powdercoat them. Dont! But im sure he can make them with the offset you want. The Gts lookalike rims is another story.
Well I asked Andrea Roin if he could vary the BS and he said NO.
Appreciate all of the input gentlemen. I will send a note to Marvic. If it doesn’t work out, then I may just stick with the original Campagnolo’s which are great…. though I really like how the wider wheels fill out the flares better and the car also handles significantly better.
Marvic will not (cannot) alter backspacing, their wheels are sand cast and it would require all new molds. I have Marvic wheels, GT5 wheels here and GTS flares, but may be a while bfore I can find time to off all that up for measurement. Start with the distance from the flare edge to the hub and we can figure the rest out. FYI the Grp 4/GT5 wheels will require longer studs.
I do like the 10" GTS Campi on the GTS and you can always use a thin spacer to improve aesthetics.
that’s a great thought on the spacers I had not considered it!
Spacers for Pantera info
This seems like Alchemy on a stock fender car to me?
You might be able to clear all the suspension on the internal side in the rear, maybe but I don't see that from happening in the front?
If that could have been done, the "factory" would have done it at least on the race cars. They were not morons. I don't see any evidence that it was tried and successful? Maybe I just look in the wrong places?
When you screw around with different width wheels in the front, you are messing around with the scrub radius. That effects steering effort and the wide fender cars also have an issue with even 10" wheels in front "chattering" the steering even under light loads.
As it turns out, with the stock suspension in front, the 8" Campi has the best geometry.
So really if you can do this, it appears you will be the first so maybe write a book about the adventure and the new people that you meet along the roadside as you experiment?
I found that there are a lot of pretty smart homeless people that I met while waiting for the tower to come and get me.
Over the years I found 2 things I would not do again when building a car:
#1 : lowering the car to make it a pain
#2 : putting wide wheel/tire combinations on the car that look great when sitting there but interfere with drivability..
I rather trade cool looks for a great and worry free ride!
@LeMans850i posted:Spacers for Pantera info
thanks!
