Choosing the Right Nozzle and Orifice Size for Car Washing

When it comes to detailing, the right tools make all the difference. One of the most overlooked yet essential components of a safe and effective car wash is the pressure washer nozzle—specifically, the nozzle tip angle and orifice size. This guide breaks down everything you need to know to make the best choice for your setup.

Why Tip Angle Matters: Safety First

We carry only the 25-degree (green) and 40-degree (white) nozzles because they offer the safest spray patterns for automotive use. These wider angles are gentle on your vehicle’s paint, reducing the risk of damage from high-pressure, narrow streams.

? Need a refresher on nozzle tip colors and spray patterns?
Watch this visual and verbal guide (also available in our product listings).

Understanding Orifice Sizes

What Is an Orifice?

The orifice size refers to the opening inside the nozzle that controls how much water flows through. It plays a direct role in determining the pressure (PSI) and water flow (GPM) coming out of your pressure washer.

Originally, we offered only a 4.0 orifice, but now we also carry 3.0 and 3.5 sizes to better support the most commonly used pressure washers in the detailing world.

How to Select the Right Orifice Size

Choosing the correct orifice size depends entirely on your pressure washer’s specifications.

Use the MTM Calculator

We highly recommend using the MTM Nozzle Calculator. Just input your machine’s PSI and GPM, and it’ll suggest the most suitable orifice size.

✅ Tip: If your calculated orifice size falls between two options, always round up.

Why? Because a slightly oversized orifice allows better water flow and cooling. An undersized one could restrict flow, potentially damaging your pressure washer’s pump.

Ideal Specs for Car Washing

For washing vehicles, your goal is low pressure with high water flow. A few pressure washer models that meet this ideal setup include:

• Kranzle (select models)

• Active Pressure Washers

• Ryobi (new low-pressure model coming soon)

Why Nozzle Size Matters (via Obsessed Garage)

Here’s a great breakdown from Obsessed Garage on why the correct nozzle is so crucial:

• A pressure washer doesn’t generate pressure on its own—it simply moves water.

• The nozzle creates pressure by restricting flow.

Here’s what happens if you get it wrong:

The sweet spot for vehicle washing?
? 1,000–1,200 PSI with the highest GPM possible.

Real-World Example: Josh’s Ryobi (He works here)

Let’s walk through a common scenario.

• Josh owns a Ryobi RY141820, rated at 1800 PSI / 1.2 GPM.

• The MTM calculator recommends a 1.7 orifice, which we’d round up to 2.0.

• However, Moreman’s chart recommends a 3.0 orifice for this exact model.

Why 3.0 Works:

• Reduces PSI to around 1090

• Increases GPM to around 1.4

• Keeps the system cool and flowing well

So, if your customer has similar specs and you're waiting on the 2.0 to come back in stock, a 3.0 orifice is a great alternative. Just make sure to inform them it will reduce pressure slightly—but that's often a good thing for car washing!

Quick Note on MTM Foam Cannons

Here’s something that might be obvious to some, but is often missed:

MTM Foam Cannons come with:

• A 1.25mm (3.5) orifice pre-installed

• A 1.1mm (3.0) orifice on the side

If you're using an electric pressure washer, swapping to the 1.1mm (3.0) can drastically improve foam performance and overall results.

Final Thoughts

Getting the right balance of pressure and flow is key to safe and effective car washing. Choosing the correct tip angle and orifice size ensures you’re not only protecting your paint but also extending the life of your pressure washer.

If you ever feel unsure, use the calculator or reach out to us—we’re happy to help guide you to the right setup.