FAQ – What is PCD, and why does it matter?:

FAQ – The Pitch Circle Diameter (PCD) is the diameter of the circle which passes  through the centre of all the studs, wheel bolts or wheel rim holes. PCD is important because it is the measurement needed to establish which wheel rim and/or suspension units you require. Frustratingly the PCD is rarely stamped on the wheel rim and is not present on the hubs/drums either, so the only way to correctly verify your PCD in many instances is to measure.

 How do I measure my PCD?:

FAQ – When measuring PCD there are multiple factors involved, the first one is how many stud/bolt holes does your wheel have? We have seen wheels with 3, 4, 5 & 6 stud holes but by far the most popular, accounting for the vast majority of our sales and calls are the standard 4 & 5 stud variants. If you have a 4 stud PCD then the measurement is relatively simple. If you was to establish the holes in the 12, 3, 6, 9 o’clock position, you would then take a centre to centre measure from one hole to the hole directly opposite (12-6 or 9-3 o’clock) for example. This measurement would ideally be taken in both imperial and metric units as PCD measurements can be either standard and are often very to each other. For even more information you could also measure the size of the centre hole of the rim (the largest hole, where the hub cap comes through), and even the size of the studs or bolts uses to fix the wheel. All of these measurements combined will increase the likelihood of us establishing which PCD you require.

FAQ – If you have a 5 stud the process is slightly more complex but the number of options is generally more limiting therefore a conclusion can often to drawn from a small number of measurements. Due to the nature of 5 stud PCD the o’clock positioning technique used on 4 studs does not work in the same fashion. We recommend choosing one stud and measuring directly across, there will not be a stud there but you can imagine the circle line which will travel through the centre of the 5 studs, and will intersect with your measuring tape. That is the ideal measurement but is often hard to attain to any reliable accuracy. Therefore we also recommend taking the following measurements; the centre hole size, the stud/bolt size & possibly a measurement from one stud to the stud next to it.

For further information with images showing the above advice and to see the most common PCD sizes pictures please feel free to visit:

Working out Pitch Circle Diameters (PCD)

How do I measure my brake shoes size?:

FAQ – We get asked this question multiple times per day and the answer is very simple and requires minimal effort to attain the correct answer. To ascertain the exactly brake shoe size you require there are only three pieces of information you will need, often only two of these are required to confirm which size you need to order. Firstly; what brand of brake shoes do you require? Knott and AL-KO shoes often say the manufacturers name on them, if they are indeed genuine. You can also confirm this by the type on mechanism uses to adjust the brakes (see paragraph below). The next piece of information you require is the measure of the inner diameter of the brake drum, if this is 200mm for example you can take this information forward to the next measurement. The third and final measurement you require is the width of the brake shoes, this is very simple and combined with the manufacturer can often prove sufficient for us to recommend the correct size for you to order. If your shoes are 50mm wide and you combine this measurement with the before ascertained 200mm then your shoes width would be 200 x 50mm.

There are various sizes available for: Knott Avonride shoes including;  160x35mm, 203x40mm, 200x50mm, 250x40mm and 300x60mm.

AL-KO shoes include; 160x37mm, 200x35mm, 200x51mm & 230x61mm

For further detail and images please see:

Identifying Trailer Brakes


How do I identify the manufacturer of my brakes?:

FAQ – Customers often contact us asking for parts such as; brake shoes, back plates, brake cables ect… without knowing the manufacturer of their brakes before hand. There are two main brake/suspension manufacturer in the UK which are Knott Avonride and AL-KO Kober. There is also BTP which has a much smaller market share, and as of 2018 is being amalgamated into AL-KO. There are various ways of assessing whether your brakes are Knott or AL-K0, but these are the main tell tail signs. What letters or symbols are pressed into the hub cap? Often AL-KO axles have hub caps which simply say “AL-KO”. Knott can be more difficult as they often either blank or use a single letter pressing denoting the series of drum used in production. The gold standard way for establishing the manufacturer is by assessing the adjustment method required at the rear of the back plate. Knott backplate’s use a nut on the rear, and a spanner or socket is required to make adjustments. AL-KO use a spindle wheel mechanism which you can see though a very small access hole, to adjust these brake a small flat head screw driver is required. You can also use the pattern pressed on the cable cover plates, if this is flat and unpressed it is most likely an AL-KO plate. The Knott Avonride cover plates have a slightly raised arrow shaped pressing which is used the distinguish them.

For further details and images please see:

Identifying Trailer Brakes


How do I identify my trailer coupling?:

FAQ – Customers often contact us with issues with their couplings, and are seeking advice on replacement parts or whether to just replace the whole coupling. Before we can give further assistance however we often need further details regarding the coupling, such as the manufacturer, model, weight rating ect… The reason we ask for further details is often to simply identify the exact coupling, so we can advise on parts availability and/or a suitable replacement coupling.

Key factors in assessing your coupling:

  • What brand is the coupling? (Knott Avonride, Bradley Doublelock, AL-KO, Indespension).
  • What is the weight rating of the coupling? (2750kg, 3500kg, 1700kg).
  • What model of the coupling do you have? (Knott KFG35, Knott KFG27, Bradley Doublelock HU3HE, Bradley Doublelock HU12).
  • Is your coupling a pole coupling or a delta coupling. Most trailers use a standard delta coupling which is mounted to an A frame. Some trailers such as boat trailers often use pole couplings.
  • If you do have a pole coupling, and are needing a replacement it is also crucial that you know the size on the box section this is mounted too, (60mm, 70mm, 80mm, 90mm or 100mm).

The most common parts requested on couplings are the damper, energy store, drawtube, coupling head and bellows.

How to identify the parts you require:

Identifying Coupling Parts

Why is my trailer banging when I brake my vehicle?:

Why is my Trailer banging when I Brake?

How do I change the damper on my Knott coupling?:

Replacing a Damper for a Knott Coupling

How do I change the damper on my Bradley coupling?

Replacing a Bradley Damper

I need to change the coupling head on my Indespension Triplelock coupling but the bolts are hidden:

Triple lock head fitting/replacment guide (Braked coupling)


What is the difference between Erde and Daxara trailers?:

FAQ – We often get asked this question just before customers place their order for their brand new trailer. We list both Erde and Daxara trailers for sale on our website and customers are often confused as to the differences, mainly the price. Erde and Daxara are first and foremost the same company, but they have slightly different positions with the companies range. Erde produce lighter duty trailers with a single skinned sheet metal construction. Daxara’s have the same physical dimensions as their Erde counterparts but offer a few extra features. Daxara’s use a stronger and more robust double skinned sheet metal construction. All parts such as ABS hard tops, raised side panels, jockey wheels ect… are compatible across both brands so do not let this factor in your decision of which best suits your needs. In conclusion, both brand are very similar but Daxara does offer some slightly different features as mentioned above. The majority of light duty trailers we sell are Erde’s due to the generally lower pricing structure when compared with Daxara’s, there are however specific occasions customers require the extra features provided by Daxara trailers, and in this case we have no hesitation is recommending them.

I have bought a second hand trailer and I need some new wheel bearings can you help?:

FAQ – We often hear similar questions to this and there is no straight forward answer. Wheel bearings are crucial to the reliability of your trailer but are often neglected, causing very expensive and potentially deadly mechanical failures. We have a comprehensive range of wheel bearings in stock varying from the smallest Erde wheel bearings right up to the largest sealed units fitted to large Ifor Williams trailers. For us to assist with wheel bearing queries we require as much information as possible, such as; Bearing numbers (ideal!), hub/drum manufacturer, Axle manufacturer, PCD of the hub/drums, is it taper rollers or a sealed bearing you require?

The reason we ask for this information is identifying a bearing with being able to see it can be very difficult. Ideally you would remove the existing bearings from your hub/drum and after cleaning them the bearing numbers should be clearly visible. From this number we can often identify the bearing instantly. Without these numbers we then have to try and identify the hub/drum and from there then identify the bearing used with these. You can also measure the bearings but this is not recommended unless you have very accurate measuring equipment and know the correct measurement required. If you are finding identifying your bearing difficult then not not hesitate you send us a photo for the bearing your require, please take as many as possible and please include the drum/hub & send them to Info@towingandtrailer.co.uk whith your name and contact details.

Can you carry out repairs on my trailer?:

FAQ – This is another question we hear frequently and the answer is YES. We have some of the best equipped trailer servicing facilities in the country leading to us have full QS registration with the National Trailers and Towing Association, which is the governing body of towing here in the UK. No job is too small, we often change customer jockey wheels, coupling locks, lights ect… whilst they wait. Similarly not job is too large, we have a strongly founded reputation for completing jobs most workshops would not attempt. Recently we have completed 10+ full trailer conversions/restorations. We have renovated 1970s Rice horse boxes into fully road legal trailers with modern running gear ready for their owners to transform them into everything from a mobile sauna to prosecco and gin bars. We have also stretched our extensive facilities to the max by carrying out full running gear conversations for 40ft+ Airstreams which have been freshly imported from the USA.

If you have any questions on repairs, servicing or conversions then do not hesitate to contact us on 01909 473749 or info@towingandtrailer.com

Do I need brakes on my trailer?: FAQ

FAQ – The answer to this question is based on two factors. Firstly the law, and secondly is your personal needs and requirements. The law stipulates that any trailer grossing over 750kg requires a full overrun braking system to be fitted to be road legal. Therefore the first question you need to answer is, how much weight will you be carrying including the weight of the trailer? If this is over 750kg then you require a full overrun braking system, preferably of an appropriate weight. The harder decisions lay around the 550-750kg area, both of these weights are available in both braked and un-braked variants. Although many customers naturally navigate towards the un-braked suspension they could still be braking the law. Cars have two towing limited (see V5), these limits show both the braked and un-braked towing capacity for the particular vehicle. Larger cars which are regular used as tow vehicles such as; Land Rover Defender, Range Rover, Discovery’s, Land Cruiser, Ford Rangers ect… Have 3500kg (Braked) and 750kg (Unbraked) limits. However a much smaller vehicle such as a Vauxhall Corsa (2016) has a 800kg (braked) and 550kg (un-braked) limit. If you therefore bought 750kg unbraked suspenion and maxed out the capacity you would therefore be braking the law, but the same weight would be perfectly legal if the trailer was 750kg braked.