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Choosing the Right Rims for Trailers, Trolleys & Equipment
Choosing the correct trailer rim is critical for safe towing, correct tyre fitment, and long service life. Whether you’re building trailers, replacing worn rims, or specifying wheels for seasonal boat use, getting the basics right avoids clearance issues, premature wear, and WOF failures.This guide explains how to choose trailer rims for New Zealand conditions, covering rim types, sizes, stud patterns (PCD), offset, and common applications for trailers under 3500kg, as well as agricultural and non-road equipment.
Types of Trailer Rims
Trailer rims are designed for different environments and duty cycles. Selecting the right type depends on how and where the trailer or equipment is used.Galvanised Trailer Rims
Galvanised steel rims are the most common choice for NZ trailers. The hot-dip galvanised coating provides strong protection against rust and corrosion, making these rims well suited to boat trailers, jetski trailers, agricultural trailers, and general commercial towing.
They are particularly popular in coastal areas and for trailers exposed to water, mud, or rough surfaces.
Alloy Trailer Rims
Alloy rims are commonly used on road-use and light commercial trailers where reduced weight and a clean appearance are important. They are popular on box trailers, car trailers, and premium builds.
While alloy rims can be used on boat trailers, trailers that see frequent immersion or harsh coastal exposure often use galvanised rims for long-term durability unless marine-grade alloy is specified.
Painted Steel Rims
Painted rims offer a cost-effective option for trailers and agricultural equipment operating in moderate conditions. They are suitable for dry-use trailers and machinery where regular inspection and maintenance are expected.
Plastic Rims
Plastic rims are designed for light-duty, non-road applications such as trolleys, carts, and handling equipment. They are not suitable for road-going trailers or high load capacities.
Integral Bearing Rims
Integral bearing rims combine the rim and bearing into a single unit and are commonly used in agricultural applications such as feeder troughs and mobile farm equipment. These rims are not intended for road trailers.
Choosing the Correct Rim Size
Rim size must match the tyre size and suit the trailer’s load requirements.Most light trailers in New Zealand use 13” or 14” rims, though smaller trailers may use 10”–12” rims. The correct rim size is determined by the tyre specification, for example, a 175/70R13 tyre requires a 13” rim.
When selecting rim size:
- Match the rim diameter to the tyre
- Ensure the tyre load rating suits the axle rating
- Confirm there is sufficient clearance under guards and chassis
- Keep matching rim sizes across each axle
Stud Pattern (PCD) Explained
What is PCD?PCD (Pitch Circle Diameter) refers to the number of wheel studs and the diameter of the circle they form. The rim must match the hub’s PCD exactly.
Common NZ Trailer PCDs
Some of the most common stud patterns used on NZ trailers include:
- 5×4.5” (5×114.3mm) – very common on light trailers
- 4×4” – smaller trailers
- 6×139.7mm – heavier applications under 3500kg
If you’re unsure of the PCD, it must be measured before ordering rims.
We recommend using our step-by-step video guide: How to Measure the PCD of a Trailer Rim
As a general guide:
- On 5-stud hubs, measure from the centre of one stud to the outside edge of the stud two positions across
- On 4-stud hubs, measure centre-to-centre across opposing studs
Understanding Rim Offset
What is Offset?Offset determines how far the rim sits inboard or outboard relative to the hub mounting face. It directly affects guard clearance and tyre positioning.
Common NZ Trailer Offsets
Most NZ trailers use either:
- 0 offset – rim sits centrally over the hub
- +10 offset – rim sits slightly outward
- Tyres rubbing guards or chassis
- Reduced suspension clearance
- Uneven tyre wear
If replacing rims, matching the existing offset is usually the safest option.
Load Rating and Trailer Capacity
Every rim has a maximum load rating, which must suit the trailer’s axle rating and intended use.As a guide:
- The combined load rating of all rims and tyres must meet or exceed the trailer’s GVM
- Load ratings are typically stamped on the rim or provided in product specifications
- Always match rims with tyres of equal or greater load capacity
Choosing Rims for Common NZ Applications
Boat & Jetski Trailers- Galvanised rims are commonly selected
- Alloy rims offer a stronger lighter alternative
- Corrosion resistance is a priority
- Correct offset helps prevent guard contact during suspension travel
- Alloy or galvanised rims are commonly used
- Appearance, weight, and fitment consistency matter
- Common PCDs such as 5×4.5” are widely supported
- Galvanised, painted, or integral bearing rims are typically used
- Durability and low maintenance are key considerations
- Plastic rims are suitable for light, low-speed applications
Common Trailer Rim Mistakes to Avoid
- Ordering rims with the wrong PCD
- Choosing the wrong offset and causing clearance issues
- Mixing rim sizes across the same axle
- Selecting rims with insufficient load rating
- Using road-style rims in high-corrosion environments
Need Help Choosing Trailer Rims?
If you’re unsure which rim suits your trailer or equipment, Treadway can help. We supply rims, tyres, and complete wheel assemblies to trailer manufacturers, workshops, and trade customers across New Zealand.Use this guide alongside our product filters, or contact the team for assistance with fitment, load ratings, and application advice.