There is a lot to consider when fitting 33″ tyres to your Toyota HiLux. If it is practical or not is another matter, but how to do it requires a little planning and (potentially) significant investment.
What is modified affects what else needs to be modified (or not) and legislation both nationally and state-specific can also determine what is possible.
Below, we step through the basics regarding what can be done to, firstly, make sure 33″ tyres fit, and secondly, make sure it is safe and legal.
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Modifications
4WD HiLux owners really are spoilt for choice when it comes to the long list of accessories and parts available.
The popularity of the vehicle no doubt makes this possible because many businesses in the aftermarket industry can recoup the large costs involved to develop these model-specific parts.
Here are some of the modifications you’ll need to make before you consider fitting 33 Inch tyres to your HiLux:
Suspension lift (2-3 inches)
Higher suspension is the minimum requirement when installing 33″ tyres.
Common practice here is a 3 inch lift, although some owners have successfully fitted 33s with a 2 inch lift, plus some other modifications (see below).
Body lift (up to 2 inches)
A body lift will provide more clearance for bigger tyres, but without serious modifications, you’re limited to about 2 inches (or 50mm).
This means hoses and cables aren’t stretched, but the steering shaft may need to be modified to address issues from lifting the body.
Levelling kit (up to 2 inches)
A levelling kit is a more budget-friendly alternative to a full suspension lift, whereby the front of the vehicle is raised via the installation of a spacer on the front suspension shock. This reduces the rake on the truck to make the front a similar level to the rear. In doing so it provides extra clearance for bigger tyres.
This can be done with or without a full-on suspension lift.
Bull bar
The HiLux wasn’t ever designed to accommodate 33″ tyres, so the bodywork requires some modifications, too.
Installing a bull bar is a good first step, as it opens up the amount of space forward of the wheel well by getting rid of the (often very low) front bumper bar.
Body Mount Chop
The steel outer skin of the body mount bracket is cut away as much as possible (as close to the rubber or poly bush as you can get), giving precious millimetres more clearance for larger diameter tyres.
Many companies sell kits comprising steel plates to be welded to where the body mount was cut, meaning a relatively simple DIY for those with a welder (and some brave pills).
It’s worth mentioning that by the letter of the law this probably makes your vehicle unroadworthy (even if it is done properly and safely).
Guard trimming
Trimming away the edges of the outer and inner guards is normally a minimum requirement as far as body modifications go, as a bigger tyre on full lock will make contact every time.
Trimming the guard prevents more significant and irreparable damage from occurring in the first place.
Wheel dimensions and offsets
Wheel size and, more importantly, width and offset play a big part in whether or not your 4×4 will rub its tyres.
A more aggressive (negative) offset will move the wheel further away from the hub, but that can also mean the tyre extends beyond the guard (which is illegal).
While rims with a positive offset will probably keep the tyre under the guard, they might increase the likelihood of rubbing on the body and suspension components.
There are dozens of wheel and tyre fitment calculators to give an idea of how aftermarket wheels and tyres fit relative to the standard setup.
Wheel diamater is largely determined by tyre availability; 16s are popular, but 17s and even 18s can be found. However, the larger the wheel the less sidewall which means less contact patch when operating at low pressures.
Considerations
Unfortunately, fitting a bigger tyre size brings with it a lot of disadvantages and it is important to be aware of them.
CV joints
Thanks to the independent front suspension (IFS) on the HiLux (and most 4x4s sold over the last two decades), one of the most important things to be aware of is excessive angles on the constant-velocity (CV) joints.
The increased angle due to the larger tyres increases the stress put onto the CV joint (especially at extremes of its operating range like full lock and suspension travel).
This can be reduced in part by installing a diff drop kit (though this is somewhat counterproductive, seeing as it is often the diff that bottoms out on sand and terrain when off-road).
Long story short; bigger tyres means decreased CV joint life. Older trucks with a solid front axle remain blissfully problem-free in this regard.
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On-road performance
Bigger tyres can be hugely beneficial off-road, but in almost every way they are a hindrance on it.
The greater weight and increased rolling diameter impacts acceleration and braking performance. Not only that, but the higher ride height also elevates the centre of gravity, having a negative impact on handling (especially manoeuvres like swerve-and-avoid).
Fuel economy will also suffer with larger tyres, both on and off-road, thanks to the additional weight and increased rolling resistance.
Lastly, your off-road-biased AT or MT rubber will generate a lot more road noise.
It might seem like overkill, but an additional set of wheels and tyres for off-road use might serve you better if space and budget allow you to keep the standard rims for road use.
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Off-road performance
For off-road use, bigger tyres win almost every time.
The drawbacks concerning acceleration and braking performance still apply (think about starting from standstill in soft sand or a mud pit), but the benefits like increased ground clearance and contact patch when tyre pressures are low normally compensate.
All the modifications above are required (or desirable) for working off-road, in circumstances where articulation is at its maximum (full-lock and full-compression). Obviously with a smaller tyre like a close-to-standard 31″ or slightly-bigger 32″, these aren’t so concerning.
A higher centre of gravity can make driving off-road very stressful, especially when at extreme angles, so while it may seem logical to go as high as you can, sometimes less is more.
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Roadworthiness and legal compliance
You can’t just go as big and as high as you like if you want to work within the limits of the law.
Each state has its own requirements that need to be adhered to. Some states require specific engineering approval for extensive modifications, though suspension lifts and conservatively up-sized tyres are usually fine without.
Your state’s transport authority will have clear guidelines readily available, but the businesses offering the accessories will also guide you in a direction that ensures modifications are roadworthy (if so desired).
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Insurance
Aside from the fact that an unroadworthy vehicle will probably have its insurance void in the event of an accident, many insurance providers have limits on what can be modified on a vehicle, and how many modifications can be made.
Read the fineprint on your policy and, if in any doubt, call them.
