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Tyre size; you can go 50mm above the biggest tyres in your model range

The question of ‘how much bigger tyres can I fit’ on your 4WD comes up regularly, and one of the most overlooked pieces of information is what the law is, and what the consequences are of running a vehicle that has tyres bigger than they are allowed to be.

VSB 14 states that you can increase the tyre size by 50mm. What it doesn’t make clear though, is that in some cases you can actually go more than this.

Here’s the exact wording “Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle.

If you are wanting to change tyre sizes, please have a read of this first – Fitting bigger tyres to your 4WD; what you need to know.

How can you fit bigger tyres?

You are allowed to go 50mm bigger than the largest tyres found in your model range. For example, if we look at our Isuzu Dmax, it came with 245/70/16 tyres, which are 749.4mm in diameter. For more information on Dmax tyre size options from the factory, look at your tyre placard on the A pillar.

If you want a tyre size calculator, check this out –  https://www.exploroz.com/Vehicle/Tyres/SizeCalc.aspx

Most people would naturally think that the maximum tyre size is 799.4mm. However, the LSU (a fancier model) came out with 255/65/17 tyres, which are 763.3mm.

Providing the changes between the models are purely cosmetic (chrome bits, fancy dashboards etc) you can go 50mm bigger than the biggest tyres in your model range. This means the maximum size is actually 813.3mm. This is perfect for us, as a 265/75/16 (one of the most popular tyre sizes around) is 803.9mm.

This exceeds the 50mm increase for the SX versions, but is within the 50mm increase for the LSU versions, and as a result we’ve gone for them. At 54.5mm bigger in diameter than the stock tyres they are a fair increase, but they actually correct the speedo and give us about 25mm more clearance everywhere under the vehicle.

For a random fact, the Dmax wheel offset is positive 33mm.

Now, bigger tyres on your 4WD are good in many ways, but like everything, have a number of downsides to 4WD modifications. Don’t forget about them when it comes to fitting them to your 4WD.

Isuzu Dmax with bigger tyres

Our Dmax with 265/75/16’s

Check with your local authorities

Please, before you fit bigger tyres, give your local road authority a call, and ask them the question. Stick within the regulations and you’ll be much better off! Is your 4WD legal?

If you aren’t sure of what’s legal, have a read of this; 32 ways to make your 4WD illegal.

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26 comments… add one
  • susan wilbraham June 6, 2019, 2:54 PM

    so will a 265 x 75 x 16 tyre fit under the front guards of a dmax with out rubbing or what would you recomend

  • Aaron Schubert June 6, 2019, 5:01 PM

    Hi Susan,

    Yes, providing the suspension isn’t sagged

    Aaron

  • Tim July 15, 2019, 7:58 AM

    Hi there,
    I am wondering if you have found any noticeable drawbacks in handling/steering or changes to the way the dmax drives since fitting the new size? Some people comment on power loss.

    I have one with stock 245/70r16’s that need replacement. I am looking at 245/75r16 as the demo I drove with 265 felt heavy in the steering. Any thoughts ?

    Cheers

  • Aaron Schubert July 15, 2019, 8:15 PM

    Hey mate,

    I swap between the tyres a fair bit. I can’t feel any obvious differences, but it does brake worse, get marginally worse economy and you do lose some power and torque. With all the weight, wind resistance and the trailer it is noticeably slower than when I got the vehicle.

    Life is a compromise; I wanted the extra clearance and will put up with the negatives

    Aaron

  • Micheal January 3, 2020, 5:51 PM

    Hi,
    Cool article, but there is something I’m questioning. When you say you can actually fit larger so long as it is within the same model range, what if those tyre sizes from the upgraded models aren’t actually on your tyre placard? I have an amarok trendline that came with 245/70/16 and that is the only size on my door placard. But looking at the amarok ultimate version, it came with 255/55/19. Therefore, a set of 265/70/17 (or similar) would be legal on a 2014 ultimate, but not my 2014 trendline. As far as I can see the changes are only cosmetic and I’d probably need flares.

    So is using any model in the range your interpretation of the rules, or am I missing something completely here? The way I interpret “Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle”, is “That Vehicle” refers to mine specifically and not others in the same year/range.

    Id love to be proven wrong, as I want to legally run a 265/70/17, but its about 4mm to big for legal purposes. Don’t want to be defected miles from home on a family trip! Or worse yet not have insurance pay out.

    Would you use the same interpretation for wheel offset? The variance in the 2014 Amarok range is nearly 30mm from memory.

    Cheers,
    Micheal.

  • Aaron Schubert January 3, 2020, 7:16 PM

    Hey Michael,

    You raise an interesting question, and one I have wondered about myself. I would say it has to be in the same year range, and the only changes could be trims, upgraded stereo’s etc, without touching any of the drive line, suspension, brakes etc etc. I don’t know enough about the Amarok’s to comment, but have confirmed my thinking on this is correct with the Department of Transport and a few engineers over here in WA.

    All the best
    Aaron

  • Gavin January 31, 2020, 11:57 AM

    I have a 2019 dmax extra cab six which comes std with 245/70/16 tyres and after reading your posts believe I can go to 265/75/16 tyre size. My dmax is automatic and was wondering if you could comment on the gear change when towing a caravan and also whether there is a difference when driving empty with an increase in tyre size. To clarify, when driving down to perth with my caravan, there seems at times to be a lot of changes between probably between 4 Th and 5 Th when towing between 90 and 100 km. Not sure I have expressed my question very well but would appreciate your thoughts

  • Adrian January 31, 2020, 6:50 PM

    Hey guys, I just stumbled upon this article regarding tyre upgrade’s. I have gone down to the Queensland department of transport and shown them this article as I also own an sx 2015 d-max ute that originally came out with 245/70r16 and I’m wanting to upgrade to 265/70r17 which puts me at 54mm 4mm over the legal limit. The department of transport Officer was a really cool lad he said that it was correct and that transport would go off the larger specs of the upgraded models. But he did say that the police aren’t educated enough in vehicle modifications and this particular legalisation in the vsb 14 regulations wouldn’t be know to them and that they would only go off your placard. What iam asking is does anyone know exactly where in the VSB 14 where it references the words manufactures vehicle range. The VSB 14 is Australian wide from what I can see. Any help locating the exact referencing would be much appreciated. As I’m going to approach my insurance company and state the referenced regulations and make sure I can get cover with the upgraded tyres cheers in advance.

  • Aaron Schubert January 31, 2020, 9:43 PM

    Hey Gavin,

    I know what you are asking. The tyres are basically the last part of the gear ratio. By fitting bigger tyres you make the motor work harder, and you will use more fuel. What weight is the van? I now tow a 2 – 2.3 tonne trailer and it works pretty hard without a remap, which may be the next port of call for me.

    See if you can borrow some tyres and test it out, but at the end of the day you’ll have to choose between economy power vs using more fuel and having less power

    Aaron

  • Aaron Schubert January 31, 2020, 9:48 PM

    Hey Adrian,

    I’m sure you’d have some disagreements with the police. I have an email copy in my Dmax stating its legal, from the Department of Transport in WA.

    However, you can read the exact wording here https://www.infrastructure.gov.au/vehicles/vehicle_regulation/bulletin/files/NCOP11_Section_LS_Tyres_Suspension_Steering_Nov_2015_v4.pdf

    Read 4.2.4. You can also confirm with various independent engineers

    All the best mate
    Aaron

  • Gavin February 1, 2020, 8:39 PM

    Hi Aaron,
    My van size length is 21 ft 7 inches and gvm of 2750 kms. I have to say the towing capability is impressive of the dmax. My last measured trip for fuel consumption was 14 litres to the 100 kms over 352 from Bunbury up sw hwy to pinjarra across the scarp to Boddington then up to Neerabup where I filled up. I have to say I was impressed. One on the main reasons I am looking at bigger tyres is for a little more clearance and better performance on sandy beaches where I spend a lot of time fishing.
    Cheers and thanks
    Gavin

  • Aaron Schubert February 1, 2020, 10:13 PM

    Hey Gavin,

    That’s some great fuel economy for sure. I would see if you can borrow some tyres to test with, as I reckon you’ll use at least 10% more fuel going to a 265/75/16.

    Whether that is worth it is up to you; you’ll get better clearance, but less power and torque, less range and you’ll pay more to travel.

    All the best mate
    Aaron

  • hasan May 8, 2020, 4:19 PM

    Dear Aeron,
    I have the LSU with 255/65/17 stock tyres, which are 763.3mm.
    Do you think if i can safely mount 255/70/18 tyre and wheel on my d-max?
    This size makes 814.2mm which is approximately 1.0mm exceeding the 763.3+50=813.3mm limit you advised.
    Is this acceptable,
    Thanks for these valuable infos

  • Aaron Schubert May 8, 2020, 4:26 PM

    Hi Hasan,

    Safely, yep. Legally, no. I wouldn’t recommend going to an 18 inch rim either. Better to stick with 16’s or 17’s for cheaper prices, better availability and they will perform better off road

    All the best
    Aaron

  • Lisa May 16, 2020, 10:10 PM

    Hi Aaron,
    I’m in WA as well, I have a 2019 Nissan Navara Np300. I have stock 255/70/16 and I was thinking going either 265/75/16 or 285/70/17
    Which would be better? With no running or any issues presenting itself
    And which could I get a 1 inch lift with?
    The Nissan Ntrek has 32.2 inch tyres
    Thank you

  • Aaron Schubert May 17, 2020, 2:15 PM

    Hi Lisa,

    I don’t know much about the Navara’s. You can go 50mm larger in tyre size than the largest in the range. From there, you will have gone up 25mm, so you can go another 25mm in lift.

    The 265/75/16 will be the more popular tyre, which means better pricing, and also better flex off road due to a greater sidewall height

    All the best
    Aaron

  • Greg Springfield May 28, 2020, 11:21 PM

    Hi, I have a 2011 Dmax with standard tyre 245/70/16. I am looking at going a bit bigger like 245/75/16 or 265/70/16. What would be the benefits of going either way. Ute is mainly used city driving with a bit of beach
    TIA

  • Aaron Schubert June 4, 2020, 8:15 PM

    Hi Greg,

    Check this out – https://www.4wdingaustralia.com/4×4/fitting-bigger-tyres-to-your-4wd/

    All the best
    Aaron

  • Daniel June 19, 2020, 8:32 PM

    I have a 2015 SX and was concerned as I wanted to upgrade to the 265/75 R16 (803mm) which is 54mm above the delivered spec.

    I was advised to check inside the manual to see what tyres are listed and sure enough it has 245/70 R16 (749) and 255/65 R17 (763) listed for the High Ride.

    I am getting the 265/75 R16 and if I am pulled over I will point to the owners manual and the 255/65 R17 (763) and state that I can go 50mm over this, the 275/75 R16 (803) is 10mm under this so it is legal in QLD.

  • Aaron Schubert June 19, 2020, 9:32 PM

    Hey Daniel,

    Cheers for that information; I never knew that it was mentioned in the manual

    All the best
    Aaron

  • beau adams July 23, 2020, 7:21 PM

    Hi,

    Does this mean that I can put a 285/75R16 tyre on a Landcruiser 76 Workmate? The Workmate comes standard with 225 tyres, but the GXL model (which I believe was only cosmetic changes) comes with 265.

    Cheers

  • Aaron Schubert July 23, 2020, 7:43 PM

    Hi Beau,

    Possibly – jump on an online tyre calculator, put the sizes in and make sure its under 50mm increase. As long as its just cosmetic changes, you should be good to go.

    I would recommend to confirm this in writing for your own peace of mind with your local authority

    Aaron

  • Moin September 17, 2020, 3:11 PM

    Hi,

    On the new dmax x-terrain the size is 265/60/18 ~ 30.5, if I am allowed to go 50mm high, that means I can go 32-33 inch tyres? mind you the tyres are already upgraded as much as possible I think ?

    Thanks in advance

  • Aaron Schubert September 17, 2020, 7:07 PM

    Hi Moin,

    50mm from the largest tyre size in the range. You’ll have to find out what that is, convert it to metric, and then find a tyre size thats under 50mm increase

    All the best
    Aaron

  • Chevy September 20, 2020, 10:59 AM

    Hey mate

    I have a 2007 SR Toyota Hilux, I’m just wondering because the standard size for the SR is 205 R15 but for the same year SR5 version it’s 255/70 R15. Does this mean the 50mm clearance can apply to my car based off the SR5 or would I have to stick my original?

  • Aaron Schubert September 22, 2020, 8:11 PM

    Hey Chevy,

    Providing they are the same vehicle in terms of structure, driveline, suspension etc and its only cosmetic changes, yep, you can go off the largest tyre size in the range. If the SR5 has different suspension, or brakes, or anything that would change its handling then no, you can’t.

    All the best
    Aaron

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