Why does the wheel PCD differ across manufacturers?

KarthikK · 26th March 2013, 23:07

We all know some common wheel PCD sizes used by manufacturers today -

- Ford uses 108 PCD
- Fiat uses 98 PCD
- Maruti uses 100 PCD
- Mercedes uses 112 PCD
- BMW uses 120 PCD
... and so on...

My question is - why do PCD sizes differ across brands? It is okay to say that car manufacturers like to maintain their individuality and stick to the size they have been manufacturing all along, but is that the real motive? I was reading up on the net about this topic and found some links for newbies, like the one below which explains what is PCD -
http://www.nice-wheels.co.uk/pcdandoffset.html

I couldn't find information on how PCD size affects vehicle performance in any manner. Does it? If it does not influence any technical aspect or provide any advantage, why do car makers stick to their specific sizes for wheel fitment patterns? Tyre gurus, please educate us on the motives of this practice.

Wouldn't it be so much easier for car makers to all follow a single universal PCD pattern? Not to forget, it would be easier for anyone trying to swap their wheels for new aftermarket alloys

.

I couldn't find any thread dedicated to this query, so I created a new one. Moderators could please merge this thread if another similar one exists.

Mr.Boss · 27th March 2013, 06:33

PCD does affect the performance in terms of strength and durability.
Wider PCD can take more load (especially the cornering force) easily than the narrow PCD (stress/load on wheel bolts and wheel will be higher). But this calls for a wider dia hub --> wider dia brakes --> large dia rims.
So to avoid this we go with narrow PCD with increased number for wheel bolts/nuts to counterattack excessive cornering force.

Least possible PCD is chosen by OEMs to keep the least possible hub & brake size.

Excuse me for a poor explanation, I could not dig out my old data for clear explanation. Let me check this weekend and post the proper data.

Thanks

26th March 2013, 23:07	#1
KarthikK Team-BHP Support Join Date: Nov 2009 Location: Bangalore Posts: 2,539 Thanked: 10,545 Times View My Garage	Why does the wheel PCD differ across manufacturers? We all know some common wheel PCD sizes used by manufacturers today - - Ford uses 108 PCD - Fiat uses 98 PCD - Maruti uses 100 PCD - Mercedes uses 112 PCD - BMW uses 120 PCD ... and so on... My question is - why do PCD sizes differ across brands? It is okay to say that car manufacturers like to maintain their individuality and stick to the size they have been manufacturing all along, but is that the real motive? I was reading up on the net about this topic and found some links for newbies, like the one below which explains what is PCD - http://www.nice-wheels.co.uk/pcdandoffset.html I couldn't find information on how PCD size affects vehicle performance in any manner. Does it? If it does not influence any technical aspect or provide any advantage, why do car makers stick to their specific sizes for wheel fitment patterns? Tyre gurus, please educate us on the motives of this practice. Wouldn't it be so much easier for car makers to all follow a single universal PCD pattern? Not to forget, it would be easier for anyone trying to swap their wheels for new aftermarket alloys . I couldn't find any thread dedicated to this query, so I created a new one. Moderators could please merge this thread if another similar one exists. Last edited by KarthikK : 26th March 2013 at 23:15.
	(2) Thanks

27th March 2013, 06:33	#2
Mr.Boss Distinguished - BHPian Join Date: Mar 2011 Location: GPS signal lost Posts: 2,811 Thanked: 7,464 Times View My Garage	re: Why does the wheel PCD differ across manufacturers? PCD does affect the performance in terms of strength and durability. Wider PCD can take more load (especially the cornering force) easily than the narrow PCD (stress/load on wheel bolts and wheel will be higher). But this calls for a wider dia hub --> wider dia brakes --> large dia rims. So to avoid this we go with narrow PCD with increased number for wheel bolts/nuts to counterattack excessive cornering force. Least possible PCD is chosen by OEMs to keep the least possible hub & brake size. Excuse me for a poor explanation, I could not dig out my old data for clear explanation. Let me check this weekend and post the proper data. Thanks Last edited by aah78 : 3rd February 2015 at 01:31. Reason: Post edited on request.
	(6) Thanks