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Old 2nd October 2006, 02:36   #1
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Default How can alloys wheels have multi-PCD??

Can someone explain how a particular wheel can work with a long range of PCDs??
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Old 2nd October 2006, 03:32   #2
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Most wheels will work only with a maximum of 2 PCD measurements, that too if they have the same number of bolts. Instead of 4 or 5, you make 8 or 10. Alternate ones are with different PCDs, thus you get two sets of PCDs.
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Old 2nd October 2006, 04:46   #3
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Vip3r is spot on, but just thought I'll ellaborate with an example.
A multi-pcd wheel can fit on two or more cars having different PCDs.

For Eg: An alloy-wheel that supports 114.3 PCD and 100 PCD has eight holes on it and is said to be of dual-PCD type. It can interchangingly be used on Esteems and Zens(using the 114.3 PCD set of holes) and on Balenos, Swifts and WagonRs(using 100 PCD set of holes).
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Old 2nd October 2006, 05:36   #4
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Quote:
Originally Posted by S@~+#0$#
Vip3r is spot on, but just thought I'll ellaborate with an example.
A multi-pcd wheel can fit on two or more cars having different PCDs.

For Eg: An alloy-wheel that supports 114.3 PCD and 100 PCD has eight holes on it and is said to be of dual-PCD type. It can interchangingly be used on Esteems and Zens(using the 114.3 PCD set of holes) and on Balenos, Swifts and WagonRs(using 100 PCD set of holes).

hi , is it necessary for wheels having multi pcd to have 2 sets of holes. accent has 100 pcd and the zen 114.3 and both have 4 bolt pattern...so should multi pcd wheels with say 100-114.3 pcd have 2 sets of differnt holes for accent and zen?
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Old 2nd October 2006, 08:01   #5
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Quote:
Originally Posted by heavy_foot
hi , is it necessary for wheels having multi pcd to have 2 sets of holes. accent has 100 pcd and the zen 114.3 and both have 4 bolt pattern...so should multi pcd wheels with say 100-114.3 pcd have 2 sets of differnt holes for accent and zen?
Here is a Kazera alloy wheel. It is flat black with machined lip.



I've shown both Pitch Circles.

The blue one (smaller one) is 100 mm PCD (Pitch Circle Diameter)
and the red one (bigger one) is 114.3 mm PCD.

Hope the picture is self explanatory.

Ram
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Old 2nd October 2006, 08:30   #6
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HF, an attempt to answer your question in lay-man terms ..

Try this: take a nut-bolt and try to fit it into a bigger size hole. Can you get it right in the center? With some effort, one could.

Now try the same with a set of 4 holes & 4 nut-bolts, to get all four centered. I dont think it is getting easier.

Now imagine doing this with a single wheel, let alone four.

It is quite logical that any machine needs parts that fit right. Bad fit, even if tightly seated, is still a Bad fit. Think - how can 4 wheels, not fit correctly, allow the car to run safely? How can the wheels be aligned correctly?


Ram, thank you. Another illustrative post from you that helped clear couple of my own doubts.

Last edited by condor : 2nd October 2006 at 08:33.
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Old 2nd October 2006, 08:41   #7
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thank you guys , that was really informative.
i have one more doubt , is there a way to find out a pcd of a wheel , is it embossed anywhere on the wheel?
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Old 2nd October 2006, 12:40   #8
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Take the wheel in your dikky and using a Vernier callipers,
measure the stud-to-next-stud distance.



If S is the stud-to-next-stud distance
and N is the number of studs in the circle
Then D, the Pitch Circle Dia. (PCD) can be computed as:

D = S*secant(90-180/N)
(all angles expressed in degrees)

So in a 4-stud/lug wheel as in most 4-cylinder small cars,
D = S * 1.414214

and in 5-stud/lug wheel as as in cars with engines larger than 2800 cc,
D = S * 1.701302

and in a 6-stud/lug wheel as in the 1960-79 Datsun/Nissan Patrol G60, known in India as the "Jonga"
D = S * 2.0

and in a 10-stud/lug wheel as in the Volvo B7R bus
D = S * 3.236068

Does this help clarify?

Ram
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Old 2nd October 2006, 12:55   #9
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So, a multi PCD wheel can only have two PCD value sets.
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Old 2nd October 2006, 12:59   #10
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pcd is called pitch circle diameter....like as ram has said the detail explanation for 4 hole....which are place at a 90 degree angle and are having equal distance from each other....like in the above diagram ..

but when 5 hole come in the angle changes to 72 degrees...
when 6 holes come in the angle changes to 60 degree...

the different pcd's like stated above are 100 mm (metric) and the 4.5" or 114.3mm (imperial) bolt circle.
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Old 2nd October 2006, 16:56   #11
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Quote:
Originally Posted by nitrous
So, a multi PCD wheel can only have two PCD value sets.
No nitrous, although it is quite rare, there can be wheels which have more than two PCDS. Also, such wheels have a cover over the holes as they don't look good.

IMO, it is difficult to design a wheel which is strong and yet has so many holes near the center. Probably why many manufacturers don't do it.
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Old 2nd October 2006, 19:53   #12
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Quote:
Originally Posted by S@~+#0$#
No nitrous, although it is quite rare, there can be wheels which have more than two PCDS. Also, such wheels have a cover over the holes as they don't look good.

IMO, it is difficult to design a wheel which is strong and yet has so many holes near the center. Probably why many manufacturers don't do it.
Would you be able to show us a pic of an alloy wheel with more than two pitch circles, Santhosh?

Ram
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Old 3rd October 2006, 06:34   #13
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Quote:
Originally Posted by ram
Would you be able to show us a pic of an alloy wheel with more than two pitch circles, Santhosh?

Ram
Ram, unfortunately I could not find any picture to prove what I have said in my earlier post. Probably I am wrong and am willing to stand corrected.

I know it will look cramped for space, but I can't see why there can't be a wheel with 12 holes when 10 is achievable. What do the experts think about strength of the wheel itself when there are so many holes close to the center?

As regards where I think I have seen one, it was on a Palio which belonged to a spectator in one of the hill-climbs in Nandi-Hills, Bangalore.
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Old 12th September 2008, 21:37   #14
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Does any one know if a PCD can be changed.

for eg: I want to change a 108PCD to 100PCD, will this be possible?
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Old 12th September 2008, 23:03   #15
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Nope. Not at all.........
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