Fitting bigger tyres to your 4WD; what should you consider?
One of the most common modifications done to a 4WD is to fit bigger tyres to it. This is done for a number of reasons, but the primary one is to gain more clearance. You won’t get far with the bottom of your 4WD dragging on the ground.
A lift kit will pick your chassis and body up, but the lowest point of your vehicle is always going to be your differential (except on independent suspension vehicles or those with portal axles).
Contrary to popular belief, a lift does not give you more clearance. The only way to gain true clearance is to install bigger tyres.
However, know that even if you can, and do bolt on larger tyres there’s a lot more to it. Everything comes at a cost, and installing larger tyres to your 4WD is no different.
If you want to know ‘Can I put bigger tyres on my car?’ this post covers everything you want to know, from the legalities to benefits and downsides and everything in between.
Why fit bigger tyres?
There are a few benefits of increasing tyre size, which I will go into below. Remember though, there are downsides of 4WD accessories and modifications; don’t forget about them.
Some of them can include voiding your insurance if your vehicle isn’t legal, not mention terrible handling too.
Consider the 32 ways to make your 4WD illegal before you change anything, as the risks are significant and this is very, very important.
I mentioned above; the only way to truly gain more clearance in your 4WD is to install bigger tyres. Actually, I lie; you could install a set of portal diffs from Mark’s adaptors, but they are extremely expensive and out of the large majority of people’s budget.
If you add 4WD tyres that are 1 inch, or 25mm bigger in diameter, the height of your vehicle goes up by 1/2″ or 12.5mm. This is important; know that your vehicle only goes up by the radius, not the diameters difference.
Most people go for 1 or 2″ bigger tyres, giving you 12.5mm or 25mm of additional clearance. It’s not much, is it?!
By changing tyre size up, more rubber is in contact with the ground. This results in greater traction, as well as greater flotation. This is why vehicles with taller tyres perform well on the beach. More surface area touching the sand means you have less weight per given area, and thus less chance of sinking!
Tougher looking vehicle
I nearly didn’t put this on the list, but the reality is, some people really care about this. A 4WD that has one or two size tyres up looks better.
If this is what you are doing the mod for though, I’d suggest you skip it; just get a set of muddies, or a new set of rims! I prefer function over form, but not everyone agrees with this!
How much difference does it really make?
Lets look at this from a number of perspectives. For every 25mm bigger overall diameter tyre size increase, your vehicle only gains 12.5mm of extra clearance. Say you go from 31″ tyres to 33″ tyres, you will gain 25mm.
Does that 25mm really make much difference? Some say it does, and some say it doesn’t.
I would say the right Tyre pressures and tread pattern would make more difference. If you go up more, from 31″ tyres to 35″ tyres, you gain 50mm clearance. This is quite a bit more, but again, nothing that Lockers wouldn’t make up for.
It’s interesting to look at the drag marks left by 4WD’s when out on a 4WD track; check it out next time you go off road. It gives you a good indication of whether your tyres are too small for the terrain.
There’s nothing wrong with dragging a diff slowly and carefully over terrain on the odd occasion, but you don’t want to smash it up against anything. This is where diff guards come into their own.
What about the 4WD you have?
This is the factor that makes all the difference. Take a 1990 model Toyota Hilux, and compare its clearance to that of a 2010+ version. They are chalk and cheese. Older vehicles, with solid axles tend to have more clearance from the factory than modern vehicles.
Does this then suggest that you don’t need to go up size tyres? Perhaps; it all depends on what you use the vehicle for!
How big are your diffs?
When I had my Hilux, I compared the clearance from the ground to the lowest point to that of a GQ Patrol. The Hilux had about 25mm extra clearance right from the get go, purely because it had smaller differentials hanging down.
Being oversprung too, they have a huge amount of additional chassis and body clearance over a GQ Patrol. Oversprung refers to the springs sitting on top of the differential, instead of undersprung, where they are under the differential (and hurt your clearance quite badly).
The point I am making is it very much depends on your vehicle, and where you drive as to whether the bigger tyres are worth it.
Are you allowed to run bigger tyres?
Please, please don’t skip this. You are responsible for driving a vehicle on the road that is safe, and legal on the road. Despite this, many people choose to ignore what the law says, and run what ever tyre size they want.
You can’t legally do this, and the ramifications are very, very serious. Ignorance is not an excuse either. 4WD tyre sizes are heavily regulated, and often in combination with suspension and body lifts.
I’m not talking about a slap on the wrist and a yellow sticker from the local policeman, I’m talking about potential jail time and mammoth medical bills to pay if your proved to have been driving an unsafe vehicle, or if your insurance company finds out and just walks away, leaving you to sort it out.
In WA, you are limited to a maximum of 50mm bigger diameter increase. However, this is just the beginning. If you go up 50mm in diameter, you have lifted your vehicle 25mm and as a result are only allowed to install a 1 inch lift kit (or have the roof height go up by 25mm further).
The total height that your vehicle goes up in WA must not exceed 50mm, unless you get engineers approval. This includes tyres, suspension lifts and body lifts. You can find out more about this at Is your 4WD legal?
The only exception to running tyres bigger than a 50mm increase on your 4WD without engineering is if there is a different model 4WD in the same year range as yours that comes from the factory with larger tyres, and has exactly the same setup, just cosmetic differences.
You can read about this here – Can you go more than 50mm diameter increase with 4WD Tyres?
If you are looking for a legal tyre size calculator, you won’t find one as it varies from state to state. Instead, find out what your local regulations are and go from there.
Are wider tyres better?
This is a can of worms. One that I am loathe to touch on, but I will anyway! When you see 3 tonne Land cruisers just idling down a super soft beach on the factory skinnies (or cheese cutters) it gives you an indication of the capability of a tall, skinny tyre.
On the other hand, a 10.5 or 12.5″ wide tyre also does extremely well off road. Personally, I wouldn’t go wider than this. Remember that your traction and floatation come primarily from the length of the surface area touching the ground, not the width.
Wide tyres might seem like they would spread the load even more, but then you have to bulldoze sand, mud, snow etc out of the way, just so your tyre can continue moving.
This is very much a personal thing, depending on your driving conditions and requirements. To me though, there’s not much point going over 12.5″ wide.
What are the disadvantages of bigger tyres?
I will start off by stating our 80 Series Land Cruiser has 285/75/16″ tyres on it. This is one size up, and gives us a small amount of extra clearance.
I could have gone bigger tyres, but there are many, many reasons I didn’t. There are plenty of negatives to fitting bigger tyres on your 4WD, which I will go into below.
The most important thing to know when you get in a 4WD with different tyres is that the speedometer may not be accurate. If you purchase a second hand 4WD and the owner doesn’t tell you about it, you run the risk of getting a fine, or worse!
Your speedometer, trip meter and odometer will be out by the percentage of size increase. If your diameter increases by 50mm (31″ to 33″ or 33″ to 35″) your speedometer will be out by roughly 10%. This varies considerably from car to car, but its something to pay attention to.
By law, your speedo can only be out by 10% (seems a bit ridiculous that new cars can come out with 10% variation), but its something to be aware of.
This also messes with your fuel economy calculations. You can still work it out; have a read of this – How to accurately work out your 4WD’s fuel economy.
Less power and torque
The tyres on your 4WD are essentially the last gear in your gear train. It’s not too different to changing a sprocket in a chain drive; the output power and torque will change. By fitting larger tyres, your vehicle will do less revolutions per kilometer, but it has to work harder to do so.
Again, this is very much vehicle dependent, but for most vehicles there will be a noticeable difference in power and torque. In a diesel 4WD, sometimes this is less obvious as they seem to just tractor along, but it is evident.
My 2.4 petrol Hilux used to lose a substantial amount of power every time I threw the 33’s on.
The 80 series turbo diesel loses a bit of power and torque, but its not as obvious.
The easiest and most accurate way to see what difference has been made by changing tyre sizes is to check via an EGT (Exhaust Gas Temperature) gauge.
A bigger tyre makes your engine work harder, and this translates into hotter exhaust temperatures. Our 80 series went up by roughly 20 degrees throughout the range when we installed the larger tyres.
Possibly the primary reason for restrictions on fitting bigger tyres is the reduced braking capacity. As the tyre diameter increases, your braking capacity decreases.
This is a serious concern; your brakes need to work as well as possible. So long as you stick within the legal requirements of your state though, you won’t have an issue.
Increased stress on your driveline
Everything that indirectly attaches to your tyres is put under more stress when you fit bigger tyres. This includes your CV’s, steering box, steering shafts, axles and differentials.
Many people will not break components on standard tyres (especially CV’s) but as soon as they go up a few tyre sizes the breakages happen on a regular basis.
Increased fuel consumption
Some people will argue with me here, saying it makes no difference. It may make very little difference if you are fortunate (generally the vehicles with plenty of power), but if your engine has to work harder to turn the new wheels you are going to use more fuel.
When you work out your fuel economy, be sure to factor in the tyre size difference. If you do 90km on the trip meter, and your tyres are 10% bigger, you’ve actually done 99km.
My Hilux went up at least a few litres per hundred kilometers, which was expected because the poor engine was already working hard as it was. The difference in our 80 series is slightly less noticeable, and I think at 100km/h it actually uses less fuel do to the revs being more centered in the torque curve.
Please don’t fit bigger tyres without accepting the risk that your fuel economy may get worse!
You know those yellow stickers that get handed out regularly, which basically say your vehicle is not roadworthy? Bigger tyres are one of the easiest ways to attract attention to your 4WD, and are often the reason for yellow stickers given to 4WD’s.
However, a yellow sticker is the least of your worries. If you are driving a vehicle that is not compliant with the local regulations, your insurance company can walk away from any claim you make. If you rear end a Ferrari, or you seriously injure yourself, you could end up with a massive bill that you have to pay.
Even worse, if you are found to have caused an accident that injures (or kills) someone because of the bigger tyres (or other illegal modifications) you could even go to jail. It’s not worth it – do things by the book!
There is a reason that 4WD’s come out with the tyre size that they do. You might be able to fit the next size tyres on your 4WD, but go a couple of sizes up and things will start to get tight. The first thing you will notice is that the tyres foul on the inner guards (usually at the front) or the bull bar.
If it is only minor scrubbing you may be able to get away with it, but remember to consider when the suspension flexes upwards it will move closer to your guards. The only way to fix this is to modify the 4WD, which isn’t impossible, but its a steep slope that is hard to stop yourself on in both time and money.
Gateway to more modifications
Bigger tyres usually result in further modifications. People find they aren’t happy with the power difference, and start looking for mods to make their vehicle make more power. If the tyres don’t fit properly, the next step is suspension or body lifts, or to trim the guards.
Believe me; once you start this slippery slide of 4WD modifications, there is no getting off! I don’t say this to put you off installing bigger tyres, just to make you aware of the potential expenses down the track!
Higher centre of gravity
The ultimate 4WD has a low centre of gravity, and plenty of clearance. For every size tyre that you go up, your centre of gravity also goes up, making it more likely for your vehicle to roll if something was to go wrong.
The moment you run larger tyres, you open a window for warranty problems. A lot of 4WD manufacturers will decline any driveline warranty claims based on running larger tyres, so watch out. There are cases where aftermarket accessories void your warranty, and bigger tyres are a common cause.
Alternatives to fitting bigger tyres
Ultimately, bigger tyres are fitted to make a 4WD more capable. The thing is though, there are many ways you can do this. For example, a locker will make your vehicle immensely more capable. If the decision came to it, I’d keep my vehicle legal and install a locker instead.
Having installed ELockers not too long ago, I know they have made our 80 series a lot more capable than the tyres ever did.
Another alternative is to change the tread pattern. Muddies will give you significantly better traction than road or all terrains. However, match the terrain you drive on the most to the tyres you buy.
As always though, this all comes down to your individual circumstances. Where you drive, how often you drive, how far you want to go etc!
What size tyres should you run then?
4WD tyre sizes vary considerably depending on the vehicle you own, and the wheels it came with. There is no legal tyre size calculator, asides from doing your own research into what comes as factory, and then looking at the local law and going from there.
That said, the tyre size you end up with should suit your driving. A 6 inch lift and 35 inch tyres might look good, but it’s not really suitable for touring around Australia. How often do you need bigger tyres? Could you get away with something else?
I usually suggest one or two sizes bigger than factory (if this is legal) with some decent tread. This is either All terrains, or Mud terrains. Not sure what to get? Check this out – All terrain tyres vs mud terrain tyres.
Above all, stick within the legalities; its not worth the risk.
Looking for something else to read? Have a look at 42 things you must know about 4WDing.
My Dmax doesn’t list the larger tyres on the nameplate either, but I did specifically ask this question to the department of transport over here in WA, and received the below response:
Sorry for the delay in replying to your email.
We receive a lot of enquires in regards to tyres as it can be confusing to some, but I will try to answer your question simply.
The statement below is from the National Code of Practice, Vehicle Standards Bulletin 14 (VBS 14) LS section relating to the size of optional tyres to be fitted to a 4WD passenger vehicle.
Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the
vehicle manufacturer for that vehicle.
As the statement says ‘any tyre designated by the vehicle manufacturer for that vehicle’, this will include optional tyres for the make and model.
The Isuzu Dmax has several options in tyre sizes and VSB 14 allows an increase of the rolling diameter over the optional tyre size, by 50mm on a 4WD passenger vehicle.
As you have said that the difference between the two Dmax models is only cosmetic and not structural, (different brakes, suspensions and axles), you can use the largest tyres fitted to a Dmax as your reference point when calculating the size of tyres allowed.
In short yes you can run 265/75R16 tyres (804mm diameter) on a 2016 Isuzu Dmax, as it is only 41 mm larger than the largest manufacturers option.
I hope this helps.
A/ Team Leader | Driver and Vehicle Services | Department of Transport
21 Murray Road South, Welshpool WA 6106
Tel: (08) 92163844 Fax: (08) 93505579
Email: blanked firstname.lastname@example.org | Web: http://www.transport.wa.gov.au”
I carry this email in my Dmax at all times, for the odd chance that I’d ever get questioned about it. I have also had the GVM upgrade done, and signed off with the larger tyres. I’m sure the engineer wouldn’t have been willing to sign it off with those tyres if it wasn’t legit.
I think you’ll have a hard time getting a straight answer out of any insurance company, and even more so a tyre shop.
It’s frustrating that these things aren’t clear, but I would confirm with your relevant department in writing (as I did) and then go for it once you are satisfied.
All the best
Thank you for so diligently answering people’s questions in the comments after so many years. I have done my best to do my own research but am still in a grey area.
My question is about the GXL and Workmate 79 series (dual cab). The GXL comes with 265/60R16 (777m diameter) tyres as standard; however, the Workmate version comes with tall-and-skinny 225/95R16s (833 diameter) from factory. Therefore, the maximum tyre diameter for both trim levels is theoretically 883mm (I am specifically looking at 315/75R16s (879mm)).
By the same logic as your DMAX, I believe it should be legal and roadworthy for me to run 879mm tyres on the GXL thanks to the 833mm tyres available as standard on the Workmate. To my knowledge there is no mechanical difference between the two trim levels – just a bit of carpet, electric windows, and a very expensive dashboard clock.
The reason for my uncertainty is that the GXL’s tyre placard DOESN’T list the workmate’s 225/95R16 – only the 265/70R16. Similarly, the Workmate tyre placard doesn’t list the GXL’s 265/75R16. Does your SX Dmax’s tyre placard have the LSU tyre size listed on its placard, or is it the same situation as the 79 series?
Also, have you managed to actually get your local state transport authority (or insurer) to affirm that the larger tyre size is legal and roadworthy? I tried explaining the situation to my insurer (Club4x4), but they declined to give a specific answer . Perhaps I should try and get an answer out of TMR (Qld).
I’ve also contacted a number of tyre shops. So far all of them have declined to fit 315/75R16s to my GXL, even if I explain the situation above. Then, I asked if I simply had a Workmate instead of a GXL, would they be willing to fit them, and of course they said yes…
Surely there must be some way to come to a definitive answer!
Thanks Aaron, I’d appreciate your insight
Yes, you can but check with your local road authority to make sure there are no issues.
All the best
If my car came out with 18inch rims can I change them to a 17 inch rims?
It really depends on what its rubbing on, and how much you want to spend. You may find your suspension has sagged, or that you have the wrong offset rims. Fixing either might make the problem go away.
I would start with taking some measurements, and working out where its touching. Relocating the mud flaps is generally the easiest job, which might buy you enough space but if its rubbing without any flex involved then fixing the issue might not be so easy, as you’ll need a lot more clearance.
Some gentle persuasion with a hammer in the right hands can be a solution too. I would not recommend a body lift
All the best
I’ve got an issue with my big wheels rubbing quite bad on my hilux when I turn. It’s pretty standard apart from the wheels just wondering how to fix this, grinding, sledgehammer, body lift etc. Any feedback is appreciated.
It will change by the difference in diameter. Look at a tyre size calculator and see how much bigger it is. I’d also confirm that its legal in your state before changing anything.
Lastly, find someone else who has done this (guaranteed there will be a few on Facebook) and ask them if it changed much. I haven’t had much experience with the 6 speed.
All the best
I’ve got a 17Dmax 6sp auto and have just fitted a 2″lift and was thinking of going ul to 265/70 16. I know it’ll give me a bit more height and I can get a tyre with a greater load rating in the 265. I know it will throw the economy a bit but will the gear changing change much, that’s what will irk me the most.
All the best
You are very welcome!
Ignore my last comment and thank you very much for your previous reply. Kind regards, Francois Siebrits
hello 4wd Australia. i was just wondering whether there is any legal implications fitting 265/75/16 tyres on a 7″ rim. Typically for on my DMax 7jj std rims, in case of an accident etc. Is it actually good to with that size tyre on a 7″ rim; won’t it cause problems with the beet?
Thanks for the feedback. 265/75/16’s are fine on a 7 inch rim, and completely legal. If you look around online, and ring some other tyre shops, they will say the same thing. The standard Isuzu rim is 7 inch, so you are good to roll.
All the best
I was looking at information on how to set up my 2017 November DMax for touring and stumbled on this article you wrote and thoroughly enjoyed reading it and found it very helpful. I was specifically also looking at information on tyre size upgrades and your article covered my questions very well. I am also changing to a 265/75/16 tyre, but I am unsure about the standard rim width, being a 7JJ standard rim. I was wondering what your Isuzu factory alloys are. The tyre shops here in QLD suggest I need a 7.5″ wide rim at least. Looking forward to hear your comment. Thank you in advance, kind regards Francois Siebrits. Ps. Thanks again for a great article.
I don’t have any specific experience with the SR5 Hilux’s, but I would measure the clearance between the rim and your brakes, and then make a phone call to NSW transport to see if you can change rim size. Assuming they fit, and its legal, you can run slightly smaller rims.
That is totally separate to offset though – you need to find out what the factory rim offset is, and what the maximum increase is (probably 50mm, but check with the department of transport again) and go from there. If you had zero offset, and could increase the track by 50mm, you can technically fit -25mm wheels
All the best
I’m in NSW and have a 2011 SR5 hilux (pre facelift) with a 2 inch suspension lift. I currently have 265/65/17s with bf goodrich KO2s on steel rims but I want it to look more aggressive. The tyres still sit a fair way inside the flares and I am happy with the tyre size but just want to know what offset is best to stay legal? The local tyre shop reckons I cant change anything due to the upgrade/increase on the caliper size on my particular hilux model. Is he full of it or on the money? Or can I change to 16s ? What do you think?
Head to Redbook, and play around with the models that are the same as yours. You’ll also have to contact the transport authority and find out what tyre size increase they allow, and go from there.
All the best
Hi i have a ln167r 2001 hilux had 16 steel split rims on it what can I go to in tyre size legally in south Australia ? 32 inch worked good on my previous hilux 33s work ok on the 01 hilux do get a minor scrubbing on full lock to the right that is all was thinking of going back to 32inch on this car I only went 33s because I never had 33s before and want ed to try them
No worries; you are welcome. I’m running Bridgestone 697’s at the moment, and had Toyo AT2’s before (still in the garage). They are 265/75/16’s
All the best