What is the 79 Series GXL Factory Rim Size?
Factory GXL Rim and Tyre Specifications
The 79 Series GXL rides on 16-inch diameter wheels as factory equipment. The exact rim width is typically 16 x 7 inches, which provides adequate support for the standard 265/70R16 all-terrain tyre fitted by Toyota. This combination represents a balanced approach to on-road manners, off-road capability, and fuel efficiency. The 265/70R16 tyre has a 265 millimetre width, 70 percent aspect ratio, and 16-inch diameter rim size, expressed in the standardised tyre notation.
In September 2022, Toyota refined the GXL specification, and both single cab and dual cab variants now come standard with the same 265/70R16 tyre on 16-inch rims. This consistency across the range simplifies spare tyre compatibility and makes purchasing replacement tyres straightforward. The factory specification provides a comfortable ride height, good visibility, and acceptable fuel economy for a diesel utility vehicle of this size.
Understanding Tyre Size Notation
The 265/70R16 notation breaks down as follows: the first number 265 is the tyre width in millimetres. The second number 70 is the aspect ratio, meaning the sidewall height is 70 percent of the width, which in this case is 185 millimetres. The R indicates a radial tyre construction, which is standard on all modern vehicles. The final number 16 is the rim diameter in inches.
Altogether, the 265/70R16 tyre has an overall diameter of approximately 791 millimetres. When you upgrade to a 285/75R16 tyre, the overall diameter increases to approximately 839 millimetres, which provides approximately 48 millimetres more ground clearance. This extra ground clearance is significant for off-road work, helping you clear rocks, logs, and deep ruts that might catch the undercarriage of a vehicle running smaller tyres.
Popular Upgrade Options
The most common upgrade path from factory GXL specifications is moving to a 16x8 inch rim fitted with 285/75R16 tyres. This combination is endorsed by many 79 Series specialists and is installed on countless build vehicles throughout Australia. The 16x8 rim width (one inch wider than factory) provides better tyre support for the wider 285 millimetre tyre, while the 75 percent aspect ratio (taller sidewall than the factory 265/70) gives a more aggressive appearance and improved off-road flex.
An alternative upgrade is the 285/70R16 tyre on a 16x8 or 16x9 inch rim. This option keeps the aspect ratio lower than the 285/75, providing a slightly stiffer sidewall that some drivers prefer for highway driving. The 285/70R16 gives less overall diameter increase than the 285/75 but still improves ground clearance by approximately 36 millimetres over the factory 265/70R16. Your choice depends on whether you prioritise off-road flex or on-road handling response.
Offset Implications and Guard Rubbing
The factory GXL rims have approximately 5 millimetres positive offset, which means the wheel mounting surface sits 5 millimetres forward of the rim's centre line. This design pulls the wheel slightly inward, minimising how much the tyre sticks out beyond the body. When you upgrade to an 16x8 or 16x9 rim, offset selection becomes critical because larger offset numbers pull the wheel further inward, while smaller or negative offset pushes it outward.
Most 79 Series owners opt for rims with 0 to 10 millimetres positive offset when upgrading. Negative offset rims are available for an aggressive stance but risk rubbing against the inside of the mud guard on full-lock turns or when the suspension compresses heavily over bumps. Test fitting one wheel before committing to a full set is wise, or consult the rim supplier about whether specific rims they sell have been proven to fit the 79 Series without rubbing.
A common configuration is a 16x8 inch rim with 10 millimetres positive offset fitted with a 285/75R16 tyre. This setup is confirmed to fit thousands of 79 Series vehicles without rubbing and provides the aggressive appearance many owners seek. If you prefer maximum ground clearance and aggressive styling, a 16x9 rim with 5 to 15 millimetres positive offset works well, though clearance at full lock turns should be verified before purchase.
Load Rating and Tyre Capacity
The factory 265/70R16 tyre carries a load index of 112, meaning each tyre supports a maximum load of 2,220 kilograms when at rated pressure. The 79 Series GVM is 3,510 kilograms, which divides into approximately 1,755 kilograms per axle on average. A pair of load index 112 tyres on the front can handle approximately 2,220 kilograms per tyre, providing adequate capacity.
When you upgrade to a 285/75R16 tyre, confirm the load index is at least 120, which provides 1,550 kilograms capacity per tyre. If the upgrade tyre has a lower load index, it is technically underbred for your vehicle. Always specify load index when shopping for replacement tyres and confirm the rating is appropriate for your GVM and intended payload. Underbred tyres will wear rapidly, overheat, and create safety risk.
Tyre Pressure and Sidewall Flex
Rim size affects the optimal tyre pressure for your 79 Series. The factory 265/70R16 tyre on a 16x7 rim should be inflated to approximately 32 PSI cold (load-carrying tyre pressure). When you upgrade to a 285/75R16 on a 16x8 rim, the recommended pressure may be slightly lower, around 30 PSI, because the taller sidewall has more flex to absorb bumps at lower pressures.
Off-road drivers often reduce tyre pressure further when traversing rough terrain, which increases sidewall flex and ground contact area. Dropping to 24 to 28 PSI on a 285/75R16 provides excellent ground contact for rock crawling and sandy terrain, but you must increase pressure back to 32 PSI before highway driving to prevent overheating and sidewall damage. Always carry a portable air compressor if you plan to adjust pressures regularly.
Fuel Economy Impact
Upgrading from the factory 265/70R16 to a 285/75R16 tyre increases rolling diameter by approximately 6 percent, which affects fuel consumption. Your speedometer will read slightly slower than actual speed because the larger tyre rolls further per revolution. Fuel economy may decrease by 5 to 10 percent in city driving because the engine must work harder to accelerate the heavier rolling mass, but highway economy is usually less affected.
The newer 1GD-FTV 2.8 litre four-cylinder engine offers better economy than the older V8 models, which helps offset the consumption impact of larger tyres. Most owners find the improved ground clearance and off-road capability of larger tyres worth the small fuel economy penalty. If fuel economy is critical to your decision, factor in a potential 0.5 to 1.5 L/100km increase when upgrading from factory 265/70 to 285/75 specifications.
All-Terrain Versus Highway Tyre Selection
The factory 265/70R16 tyre fitted to GXL models is typically an all-terrain design that balances on-road refinement with light off-road capability. When upgrading to a 285/75R16, you have the choice between all-terrain, light truck, and purely highway-oriented designs. Most 79 Series owners select all-terrain tyres to maintain versatility, accepting slightly more road noise for the peace of mind that the tyres can handle rough country.
Popular tyre brands in 285/75R16 all-terrain include Cooper, Toyo, BFGoodrich, and local brands like Kumho and Hankook. Prices vary significantly, with budget options around 150 to 200 dollars per tyre and premium options exceeding 300 dollars. Given the vehicle's focus on off-road capability, investing in quality all-terrain tyres pays dividends in traction, durability, and puncture resistance during challenging trips.
Frequently Asked Questions
What is the factory tyre size on a 79 Series GXL?
The factory tyre is 265/70R16 mounted on 16-inch diameter rims. Post-2022 models come standard with this size on both single cab and dual cab variants.
What is the most popular upgrade tyre size?
The 285/75R16 tyre on a 16x8 inch rim is the most popular upgrade for 79 Series owners. This combination provides improved ground clearance, off-road appearance, and capability without requiring guard modification or causing rubbing issues.
Can I fit a 285/75R16 tyre on a factory 16x7 inch rim?
Technically yes, but it is not recommended. The 285 millimetre tyre is wider than a 16x7 rim is designed for, and the tyre sidewall may flex excessively, creating handling issues and accelerated wear. A 16x8 or 16x9 rim is preferred to properly support the wider tyre.
How much more ground clearance do I get with a 285/75R16 upgrade?
The 285/75R16 tyre has an overall diameter approximately 48 millimetres larger than the factory 265/70R16. This increases ground clearance by roughly 24 millimetres, which is noticeable when crossing rough terrain but not a dramatic change.
What offset should I choose for an aftermarket rim upgrade?
Most 79 Series owners opt for 0 to 15 millimetres positive offset on 16x8 and 16x9 rims. Positive offset keeps the tyre closer to the body and eliminates rubbing risk. Avoid negative offset unless you have specifically tested fitment and confirmed no rubbing occurs at full-lock steering.
Do I need to adjust my speedometer when I upgrade tyre size?
No mechanical adjustment is needed, but your speedometer will read slightly slower with larger diameter tyres. The difference between 265/70R16 and 285/75R16 is approximately 5 to 6 percent, meaning your speedo might read 95 kilometres per hour when you are actually travelling 100 kilometres per hour. Most drivers accept this as the cost of upgraded capability.
