Author Topic: Wheel Bolt Length  (Read 2127 times)

Offline JHWP

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Wheel Bolt Length
« on: 19 June 2018, 21:03 »
I'm just about to fit a set of aftermarket alloys to my MK7 Golf GTD. The wheels are Rotiform IND-T in Silver/Machined and the specs of them are 18x8.5 ET45. Tyres are Michelin Pilot Sport 4 in 225/40-18. These wheels use a radius bolt seat, the same as the OEM wheels.

I'm trying to figure out if I need longer wheel bolts and if so how much longer. The OEM bolts (27mm thread length) when fitted to the OEM Nogaro wheels protrude from the mounting face of the wheel on the inside by 19mm.
When these bolts are fitted to the Rotiform wheels they protrude by 16mm so with a 3mm difference one would say I need bolts with a 30mm thread length to match the amount of thread available on the OEM set up but... having done a good bit of research the minimum amount of rotations that is recommended for a 14x1.5 wheel bolt (stock bolt for VW) is a 7.5 turns. So I checked this with my OEM wheels and I only get 6.5 turns from initial thread engagement to fully tightened at 120NM. With the Rotiform wheels I only get 5 turns. So neither are 7.5 or above, not even the OEM setup??

Can anyone advise here?

I did contact Rotiform directly and they gave me an a totally useless answer - they said I should be O.K. using the OEM bolts but if I had any concerns with the amount of thread engagement I could buy longer ones. Great info  :rolleyes: I'd like to be a bit more solid than "should be O.K." when it comes to attaching wheels to my car to be honest and I can buy longer bolts? Thanks for the the tip... I would have thought that the manufacturer would be able to confirm on what is required.
I also contacted three Rotiform dealers for advice by email and not one replied. Nice.

Thanks.

Offline jv

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Re: Wheel Bolt Length
« Reply #1 on: 19 June 2018, 21:10 »
Think you already have your answer - buy 3mm longer bolts and it's exactly as VW supplied.
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Offline JHWP

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Re: Wheel Bolt Length
« Reply #2 on: 19 June 2018, 21:42 »
Yes, initial logic would suggest this but as I have said in my post - this length does not give 7.5 rotations of the bolt which is the minimum thread penetration for a M14x1.5 bolt. What has me confused is that the OEM wheels and bolts don't give this amount of rotations either.

Offline hog_hedge

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Re: Wheel Bolt Length
« Reply #3 on: 19 June 2018, 21:52 »
Yes, initial logic would suggest this but as I have said in my post - this length does not give 7.5 rotations of the bolt which is the minimum thread penetration for a M14x1.5 bolt. What has me confused is that the OEM wheels and bolts don't give this amount of rotations either.

Who has recommended 7.5 turns? I imagine that if VW think 6.5 turns is good then it’s good. My wheels haven’t come off yet :grin:

Offline JHWP

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Re: Wheel Bolt Length
« Reply #4 on: 19 June 2018, 22:09 »
ST, KW, H+R, Tyre Rack etc.

This info is around in a good few places. Here are some examples with some info -

http://blog.moddedeuros.com/how-to-determine-the-correct-lug-bolt-length-for-your-audi-or-volkswagen

https://www.oponeo.co.uk/tyre-article/wheel-spacers-does-wider-mean-better

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=107

It certainly is odd that V.W. don't align with this 7.5 minimum turns I agree. My wheels haven't come off either but I'd prefer to be safe and not use a wheel coming off to figure out that my wheel bolts are too short. I'd prefer to figure out the correct length needed to be sure that they are long enough that my wheels definitely will not come off.
« Last Edit: 19 June 2018, 22:14 by JHWP »

Offline jv

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Re: Wheel Bolt Length
« Reply #5 on: 23 June 2018, 21:32 »
Your last link says:
*If you cannot find the vehicle manufacturer's recommended torque spec, you can use the following as a guide.

Do you regularly read about VW wheels falling off?
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Offline JHWP

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Re: Wheel Bolt Length
« Reply #6 on: 23 June 2018, 22:40 »
Your last link says:
*If you cannot find the vehicle manufacturer's recommended torque spec, you can use the following as a guide.

It does, yes. I'm unsure of what your point is exactly though. The guide mentioned does include a minimum amount of turns on the hardware in the chart but the guide is in context of the required torque of the bolts (if the vehicle manufacturer recommended torque spec is unknown) rather than the amount of turns of the hardware. The wheel bolt torque required in my case is 120NM but this amount is the same no matter what length bolts are used on my car.

Do you regularly read about VW wheels falling off?

No, I do not but I will not be running my OEM wheels when I fit my aftermarket wheels and this is why I am looking to confirm the correct length of bolt that I need to mount them safely.

I posted here looking for some advice on this from fellow members, members that I would assume would have more experience on this than myself. So far the response here has not been helpful unfortunately and with a dose of sarcasm which is disappointing. Are there any other members here who may be able to give me some constructive advice on this? I'm not looking to get into an argument about anything here, I'm just looking to figure out what length wheel bolts I need to mount my new wheels. If any other members here could help me figure this out, I would appreciate it.