Wheel nut thread length?

[Gav2504]

Does anyone know the correct thread length for an a209 with AMG wheels. When I originally bought the car the rear had M12 1.5 radius bolts with a 40mm thread and 3mm (I think) spacers.
The fronts had 10mm spacers and 45mm tapered bolts.
I've put a 40mm radius bolt through the wheel with the disc on the back (no spacer) and measured how much thread protrudes.
It's 8mm. I've measured the thickness of the hub. Which is 10mm but the last couple of mm doesn't have any thread anyway.
If the bolts go all the way through the hub and out the other side then anything over 55mm length would make contact with the parking brake.
So it looks to me that 40mm thread might be the correct size. 8mm doesn't seem like a lot but 15 mm and there's contact with the hold down springs.
Does anyone know if M12 1.5 radius bolts with a 40mm thread are the correct standard size with AMG wheels. If not what should they be?

 

[OneForTheRoad]

eBay states 26 to 28 mm thread length and a 40 mm overall bolt length.

 

[Gav2504]

eBay states 26 to 28 mm thread length and a 40 mm overall bolt length.

Thanks but that's for standard wheels.Whatever standard wheels are.
I placed the disc on the back of the wheel and put a 40mm thread bolt through and it only protrudes by 8mm. If I used 26 - 28mm thread bolts it wouldn't go through the disc. Which means it won't screw into the hub.As it will be far to short.
26-28mm bolts will fit the space saver wheel but not the alloy.

 

[Gav2504]

These are the wheels. If that helps.

 

[OneForTheRoad]

Possibly it's the seat taper that's stopping them ?

Bolts for aftermarket alloys pictured.

 

[Gav2504]

After doing a lot of research I came to the conclusion that most if not all mercedes wheels use radius seat bolts. If fitting aftermarket wheels then tapered might be required. However, my wheels are genuine Mercedes wheels that came with the car. It's a Clk200 kompressor sport. It has the AMG sports package. I have a standard space saver spare wheel which came with shorter bolts. As the longer bolts will make contact if used.

 

[OneForTheRoad]

Think you maybe need the correct wheels for the car . Obviously the offsets are all wrong .

 

[Gav2504]

As far as I'm aware they are the correct wheels. A lot of clk's have them.

 

[Gav2504]

I've checked the offset on one of the front wheels and it looks like et37

 

[OneForTheRoad]

As far as I'm aware they are the correct wheels. A lot of clk's have them.

I can't imagine why the need for spacers if they are ??

 

[Gav2504]

When i bought the car it had lowered suspension all round. I removed the wheel spacers on the front wheels and found that the tyres were rubbing on the strut.
I assumed that's why they were fitted but no need for them on the back. So maybe a previous owner wanted a wider track or wider looking wheels. I dunno. Due to the rubbing I had no choice at the time but to put them back on.

 

[OneForTheRoad]

When i bought the car it had lowered suspension all round. I removed the wheel spacers on the front wheels and found that the tyres were rubbing on the strut.
I assumed that's why they were fitted but no need for them on the back. So maybe a previous owner wanted a wider track or wider looking wheels. I dunno. Due to the rubbing I had no choice at the time but to put them back on.

Then surely the wheel bolts were changed then for longer ones . Making them too long now . The bolts on my e350 coupe were 40's with 28mm thread , they would barely poke out of the back of the front hub once tightened. Hubs being around 8mm thick.

 

[Gav2504]

If anything they are too short. That's why I originally asked the question about what size should they be? I put the brake disc on the back of the wheel and placed the bolt through the wheel and the disc. So that I could see how much thread would go into the hub. I had 8mm thread. Which doesn't seem a lot. I measured the hub which is 10mm but the thread doesn't go all the way through. It stops at about 8mm. So my bolts wont poke out the back of the hub. As they'll only go as far as the thread goes.
Personally I think that the rear radius seat ones with 40mm thread are probably the original bolts That mercedes fitted with the wheels and The fronts have been changed to 45mm thread tapered bolts due to the spacers.
If your e350 bolts only just poked out of the hub then I guess I have my answer.

 

[tode]

Hi Gav,
I'm rather worried when you say you have MB wheels on the front but are using tapered bolts . . .
AFAIK, all MB wheels use radius bolts - tapered bolts won't give a satisfactory seating.

 

[colinallcars]

Hi Gav,
I'm rather worried when you say you have MB wheels on the front but are using tapered bolts . . .
AFAIK, all MB wheels use radius bolts - tapered bolts won't give a satisfactory seating.

I agree, and the spacers don’t come into the equation as the bolts seat in the surface in the wheel.

 

[Gav2504]

I'm not using tapered bolts. The car has been off the road since beginning of 2021.
The car is a ground up rebuild. Which is close to being finished. That's why I want to know the correct bolt length.

 

[Gav2504]

I agree, and the spacers don’t come into the equation as the bolts seat in the surface in the wheel.

I know.