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Choosing wheels for your Van, Caravelle or Camper is one of those emotive subjects - here, we outline some of the pitfalls you can be faced with when contemplating those shiny new - or not so new (or shiny) - rims that instantly transform the look of your ride.

Wheel Sizes

Typical T4 steel wheel sizes are 6Jx15 ET44 (T4a) 6Jx15 ET55 (T4b)

  • 6J - refers to the wheel rim width in inches
  • 15 - refers to the wheel diameter in inches...
Fig.1 - the "deepdish" (well, slightly!!!) T4a 6x15 ET44 rim


Fig.2 - the T4b 6x15 ET55 rim


For further illustrations of standard and approved wheels please refer to Standard Tyre And Wheel Sizes.

  • ET - "Einpresstiefe" translated from German to "insertion depth" refers to the offset of the wheel in mm where zero offset means that the mounting face of the wheel is on the wheel rim's centreline. Positive offset, as applied to the T4 (Fig.3 below), means that the wheel's mounting face is closer to the kerb, whereas negative offset means the mounting face is more biased toward the brakes. A lower the offset value will make a wheel of any given width (i.e. 6J as in our example) sit further out hence the term "deepdish" (see Fig.1 above).
Fitting wheels of a lower offset value will also increase the "track", or the distance between the centre line of each wheel on any given axle (front or rear) giving benefits in handling, but increasing the strain placed on steering and hub components.

Some suspension and steering designs incorporate wheels of increased positive offset (such as the ET55 15" steel wheels fitted to the T4b) - a feature known as "negative scrub radius" first found on the 1973 Audi 80 / VW Passat which encourages steering self-correcting, beyond that of the steering caster angle (think shopping trolley), under emergency situations - heavy braking and even a tyre blow out, being examples.

Fig.3


The offset is an important consideration when choosing larger wider wheels - the offset must be reduced to compensate for the wider rim to prevent rubbing on the wheel arch - reducing it too much will cause rubbing on the inner wing and suspension components - an MOT failure!

Please refer to Non Standard Tyre And Wheel Sizes for a list of possible tyre and wheel size combinations.

The relationship between Positive Offset and steering geometry is a topic we seldom hear about these days, because it is now a common feature along with antilock brakes, but when introduced on the 1973 Audi 80 negative scrub radius steering geometry was revolutionary giving the driver more control if a tyre blew out at speed.

Fig.4 shows the line of the steering components intersecting the ground closer to the kerb where as conventional designs had the line intersecting the ground on the centre line of the wheel. This is purely due to the wheel's Positive Offset. Fig.5 shows Audi showing off the virtues of this innovation, which in it's day was a major safety selling point of the, then new, VW Audi family.

Fig.4 Negative Scrub Radius


Fig.5 Braking Stability


Additional factors to consider when choosing wheels

T4b steel wheels are load rated at 810kg with a Pitch Circle Diameter (PCD) of 5x112, with a centre hole to fit on a 57.1mm hub spigot. The T4a had a 810kg loaded 15" wheel option (which was fitted as standard on some Chassis Cab models).

Tyres have their Load Index, wheels have their TUV Load Rating. In the case of most T4 steel wheels it is 810kg, which is considerably more than typical car wheels, unless they are from the heaviest of cars.

Commercially rated alloy van wheels are case hardened, and as such will shatter if overloaded, whereas car alloys tend to be soft and maleable, and will square off, buckle and crack if overloaded. However, buyers must be wary as many car wheels do not display their TUV load rating.

Many owners have fitted car sourced alloys to their T4's and have not reported problems (yet some have, though!). This may be due to family cars becoming heavier, for the same reasons that the T4 is heavier than it's predecessors.

A VW Touran weighs in at 2220kg Gross Vehicle Weight - the T4a 800 Special has a DGW of 2320kg, whilst a Mercedes E-Class 7-seater estate has a DGW of 2360kg.

Another contributing factor is good tyre choice - when combining suitable load rated tyres with a good quality wheels they effectively become one via the tyre's bead locking into the wheel's rim when the tyre is installed and inflated for the first time.

However, some inferior quality wheels may not tolerate the combined force of the tyre bead and the increased tyre pressure necessary for heavier vehicles, making the wheel the weak link in the chain between road and vehicle in an emergency situation when the vehicle's total mass bears down on the front wheels.


Tyre Inflation also contributes to this combined strength and also serves to protect the rims from the ravages of speed humps and potholes that we often encounter. VW recommends a 3.0bar (44psi +/- 10%) pressure for any tyre which is beyond the standard size for the T4 - the same as the full load pressure of a Mk5 Golf, Touran or Passat using 91 or 94 load rated non-reinforced or extra load car tyres - the full load pressure of most Sharan's is 3.2bar (some are 3.6bar).

Fig.6



  • Pitch Circle Diameter (PCD) refers to the number of bolts or studs used to install a wheel, 5 bolts in the case of the T4 but this can vary from a 3-hole fixing upwards, depending on the vehicle make and model. The pitch is the diameter in mm of the circle that intersects the stud centres - in the T4's case 112mm, hence 5x112 (as per Mercedes and 5-stud Audi / late Volkswagen group vehicles - but not MK3 and MK4 Golf derived models which are 5x100). Fig.6 shows a typical 5-hole Pitch Circle Diameter pattern and the correct wheel bolt/nut tightening sequence.
Tightening Torque is 180Nm for steel wheels and 170Nm for alloy wheels, making sure that the central hub hole and hub spigot are free from corrosion build up - a light rub with fine wet and dry and a smear of copper grease on both surfaces will see to that. Wheel bolts should match the wheel and be of sufficient length to positively engage with the threads in the hub.

Should you wish to fit T5 wheels (PCD 5x120 - as per BMW) or Porsche wheels (PCD 5x130) on your T4, adapter plates are required. However, such spacers decrease the wheel's offset (ET) by their thickness as they count as the hub mounting face, possibly causing the wheel to protrude beyond the line of the wheelarch.

Provided such a protrusion doesn't touch the wheelarch when steering - also an MOT failure - the use of wheel arch extensions may be necessary to enclose the tyre within the bodyline - a requirement to reduce spray in the wet.

Another consideration is the sliding door - runner extensions are available or the locating studs can be packed out slightly with shims or spacers (that's washers to you and me) and sealed with body mastic.

The Hub spigot or central location collar is the flange on the wheel hub that locates the wheel it's central hub hole (as shown in Fig.3), making it easier to fit and taking the load off the wheel bolts and bolt holes on the wheel when in use. The VW / Audi standard wheel centre hole size is 57.1mm but some aftermarket wheels will have a larger hole size to cater for other marques, which should be installed with a plastic spigot adapter ring on the hub.

Wheel Summary

We have focused on new wheels brought from a stockist - beware of secondhand wheels, they could have some major defect, such a hairline cracks or major buckling which won't become apparant until later, which is sometimes too late for any redress (remember Caveat Emptor - buyer beware - when purchasing used goods from a private vendor)...

The look of your van is very much a personal thing - the purpose of this article, and it's related articles, is merely to highlight the issues that apply to the heavier T4, and more so the T5, but may not necessarily have been a concern for owners of the lighter T3 and T2.

Please by no means let this put you off buying alloys for your T4, just knowing the pitfalls - and matching with suitable tyres - could save you a fortune...
 

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I'm not sure about the load been taken off the nuts/bolts by the centre, for example a t3 standard wheel doesn't fit tight in the centre therefore the load is taken by the nuts/bolts. I'm not saying the above is wrong. I am confused as to weather or how important this is on a t4 to have spigots as a lot of spigots I've seen are plastic. T: good thread by the way.
 

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Thanks for the article - I am using a rusty original spare where my near side front alloy recently fitted with a new conti was blown and busted having hit a foot deep and flooded pot hole coming home to StAndrews the other evening
Trouble is the six spoke alloys are 12 years old now and our local ( and very good) VW dealer has put a replacement on back order
with no guarantee of delivery time.
£500 quoted for wheel and tyre it was an expensive hole to hit!
Thinking now I should replace all the alloys and use one of the old alloys as the spare.......
Any thoughts or suggestions would be much appreciatedT:)
Cheers
Airjo
StAndrews
Scotland
 

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Help me please,

I've been to our local breakers for a set of wheels this weekend but i'm stuck!
On the inside of all the wheels is the sizes and the ET rating but nowhere is there markings as to the load rating of the wheel,
I went through 9 sets of wheels and all the same.

How can i find out if the wheels come from a car or van/4x4.

Interestingly the breakers says that they are all ok to fit and load rated LOL:

Cheers
 

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Quick question...

I have purchased adapter plates so I can fit Porsche Alloys to my T4. Obviously they fit however there is no hub protruding obviously so the load is taking up by the 5 bolts? Is this safe?
 

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Bring up the old thread sorry. My allloy spoke cracked on my stock 93mv. The spare say's 38/92 ET44 6J/15H, all of that makes sense but the 38/92, what does that denote?
I found 3 other steels to complete a set, however these the 3 say 42/92. is that the date stamp perhaps?
just overly curious I guess :)
 

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Great post, I've read it more than a few time over the years now, BUT---does the T4 have a positive, negative or neutral scrub radius? I have looked everywhere and I just can't find it. Wheel size .com comparison assumes zero scrub, I'd like to know definitively what effect different wheel sizes will have. I think I need to know the kingpin inclination angle and initial scrub offset to work out how slightly different sizes (both radius and with) will affect the handling. It seems a larger radius wheel can potentially have a big effect on scrub without changing the ET. Any ideas?
 
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