Ask any question on a 4WD forum and chances are it’ll be this: “What pressure should I run my tyres at?”
And often, the answers are wildly off the mark, opinions with no science behind them.
To get tyre pressures right, you need to understand a simple but vital relationship: Pressure + Load + Speed. My mate Steve Burke at Toyo Australia calls it the Pressure Premise, and it goes like this:
- Add weight = increase pressure
- Remove weight = reduce pressure
- Drive fast = use more pressure
- Go slow (like off-road) = less pressure, because you want the tyre to flex and shape to suit the terrain
Seems straightforward, yet most advice floating around online is anything but. So where should you start?
Start with the placard, then go further
The tyre placard on your door jamb is a handy starting point, especially if your 4WD is still stock. That number is calculated based on a vehicle’s unladen and gross mass, offering a factory compromise between load-carrying, handling, and comfort.
But let’s face it, very few 4WDs stay stock for long. Add a bull-bar, winch, long-range tank, canopy, drawers, fridge, roof rack, rooftop tent—you’ve just tipped the scales, and suddenly those placard numbers aren’t enough.
Heavier vehicle = higher pressure. Simple.
Don’t guess, weigh it!
You can estimate the weight of your mods, or better yet, get it right the first time with a mobile weighbridge service. That’s what I did in Adelaide with Andrew Cowell from OnSite Weighbridge. I wanted to know what my Isuzu D-MAX really weighed—both solo and towing my dual-axle ATV trailer—and how that impacted my pressures.
Here’s what the numbers showed:
- D-MAX total: 2,766kg (just under the 3,100kg GVM)
- Trailer total: 1,083kg (well under its 1,950kg ATM)
But it’s the axle splits that tell the real story:
- D-MAX front: 1,291kg (LHS: 651kg / RHS: 640kg)
- D-MAX rear: 1,475kg (LHS: 748kg / RHS: 727kg)
- Trailer front axle: 599kg
- Trailer rear axle: 484kg
Add in a 166kg towball load and it’s clear the rear of the D-MAX is doing the heavy lifting.
Discovery Sessions may change how you think about the rubber beneath your rig.
Want to learn more? Watch the video below or Sign up here to our Online Discovery Sessions, to become a Toyo certified dealership today!
