Author By
category Posted in Kumho News
Comments with 32 comments

Nowadays, most cars tend to be front wheel drive. On a front wheel drive vehicle the front tyres are working much harder than those on the rear axle. On a front wheel drive car the tractive forces, steering forces, cornering forces and most of the braking forces are transmitted through the front tyres. Additionally most of the vehicles weight is carried by the front axle because the heavy engine and transmission components are centred there.

Assuming the vehicle geometry is within the vehicle manufacturer specifications, this concentration of workload usually results in the tyres on the front axle wearing quicker than the rear tyres. It would be wasteful, not to mention uneconomical, to replace all four tyres just because the front tyres have worn close their legal limit. So a lot of people find themselves having to replace the front tyres on their car before the rears.

There is a lot of confusion as to which axle the new pair of tyres should be fitted.

With a vehicle that has same size and fitment of tyre on the front and rear axle, the easiest (and some might think most logical) thing to do would be to just replace the front tyres. After all, they are going to wear quickest again so it makes sense to put the tyres with most tread on the front so that they last longer. For reasons of safety this is the wrong thing to do.

On wet road surfaces, the amount of grip a tyre has is directly linked to its ability to clear surface water so that the rubber in the tread can make contact with the road surface. One of the principal functions of the grooves in a tyre tread is to provide channels for the standing water on the road surface to drain away through. One could easily imagine that a tyre with worn tread grooves will not be able to clear as much surface water as an equivalent new tyre with the full tread depth.

So why is it better to have more rear grip than front grip?

To understand it’s necessary to talk a little about vehicle dynamics. During cornering, a vehicle will usually experience one of 3 dynamic states, which are understeer, oversteer or neutral cornering.

Understeer

This condition is where the tyres on the front axle do not follow the exact angle prescribed by the steering, but ‘slide’ slightly wide. See below.

Kumho Tyre   Should you fit new tyres to the front or rear?

Oversteer

This condition is the opposite to understeer, whereby the nose of the vehicle follows a tighter line than the angle prescribed by the steering. This is caused by a lack of rear axle grip. See below.

Kumho Tyre   Should you fit new tyres to the front or rear?

Neutral Handling

And this condition is where the nose of the vehicle follows the exact line prescribed by the steering angle.

Kumho Tyre   Should you fit new tyres to the front or rear?

It is very difficult to build a car with neutral handling, especially a front wheel drive car where the weight distribution is front biased. So, most manufacturers build their vehicles with inherent understeer as it is the safer handling characteristic. If a vehicle is understeering, (sliding wide in a corner), assuming maximum front tyre grip has not been reached or exceeded, adding steering angle to the wheels will result in the vehicle negotiating the corner safely.

However, when a vehicle is oversteering, most of the things one would do to try to reduce oversteer and regain control will actually exacerbate the situation.

Braking will reduce the load on the rear axle, making the rear tyres more likely to lose grip. Likewise, reducing power abruptly will transfer weight from the rear axle onto the front, again reducing rear tyre grip. The only way to counteract oversteer is to steer the front wheels out of the corner, in other words reduce steering angle. This is something which is counter-intuitive and difficult to do whilst maintaining control of the vehicle.

Conclusion

To give the best possibilities of a vehicle handling safely when fitting new tyres to a vehicle in pairs, it is advisable to fit the new tyres to the rear axle.

 

Hero photo credit : revivalsportscars.com

  1. Jerry Hone

    I always put new tyres on the back, and move the new ones to the front. Irrespective of usage, tyres degrade in sunlight. I could probably go through 3 or more sets of fronts without worrying about the rears, but the risk increases of a rear tyre failure due to UV degradation. So new tyres go on the rear and my old rear ones go on the front and I wear those out in the next cycle and I never have any tyres on the car older than 2 changes.

    Reply
  2. Hi guys, thanks for this interesting topic. I’ve been thinking about this for a while. About to change my rear tyres and fit the current front tyres in the rear whilst fitting the new tyres in the front. But after watching an online video and reading your expert advice, I suppose I’ll fit the new tyres on the rear then. Thanks.

    Reply
  3. While this makes sense in theory, it is rather redundant because no one should be using tires where 2 of them are drastically more “grippy” that it would make a huge difference. For example, I have a FWD car that has a decent amount of
    torque. The front tires get worn out at a much quicker rate than my rear. Therefore, the rear wheels will always have more thread life.

    If I follow the article’s suggestion, then I would theoretically never need to rotate my fronts and rear tires, which is incorrect as that would definitely make me wear out my tires unevenly over time. That’s why I always put my newer tires in the front so that it gives them a chance to wear out faster to match my rear ones. And once the front gets worn down more than my rears, then I switch them, and repeat the cycle.

    And to be honest, if one drives within speed limit appropriate for the road conditions, no one should be oversteering or understeering and spinning out anyhow. This isn’t a race track.

    Reply
  4. I almost feel like the rear tires being newer than front ones is dependent on, ones experience and understanding, but a theoretical test with both scenario
    Is eminent for clarity.
    I have always made sure the front tires of all my cars are newer.

    Reply
    • me too…all these while I made sure new tyres are in front. until yesterday, I had a burst on my rear right while driving at slighty more than 180km/h. my previous experience with tyre burst was at 60km/h on the slow lane(Malaysia) which I knew was going to happen coz i wanted to experience what it was like that time before I changed that super worn out tyre. so it was an easy one. back to yesterday’s 180km/h experience…that instance, I heard and felt what has just happened, immediately signalled and tried my best not no move the steering too much. while heading for the emergency Lane. since I was moving faster than the other cars, I managed to get through the other two lanes and stopped right where it should. well, thank God. I’m sure He never stopped loving me;) So after all happened, I googled about it and here I am. Confused too…what if it burst in front? wouldn’t it be hard to control as it will be uneven and steering will not be straight. during my incident, all that was n my head before the car came to a stop was to maintain that straight steering. if it happened to my front, I think I would have gone swerving left and right. p.s. worn out on rear and brand new on front. was actually heading to the tyre shop to get the rears changed as it was closing. lol.

      Reply
  5. Well, all I know is that both my front tyres need replacing, and after reading through all these comments…..I’ll go with putting the new tyres on the rear. Seems like the more safer option. Thanks guys 👍

    Reply
  6. John Ingham

    I fully agree with fitting new tyres on the rear axle of rear wheel drive cars. As for front wheel drive cars, I think you are totally wrong! You totally focus on turning through corners at too high a speed. In everyday motoring, how common is this?
    When accelerating with a front wheel drive, where is the grip required? When braking, especially in an emergency, where is the grip required for either front or rear wheel drive cars required? I’ll help you, the front wheels!
    In everyday normal driving, the grip is required essentially for reduced stopping distances. In slippery conditions it’s more common to lose grip when setting off or accelerating.
    The rear wheel grip that you talk about is more commonly required for the race track!

    Reply
    • Tom Shattock

      In this piece, we haven’t necessarily mentioned speed. We are talking about the handling balance in conditions where grip is reduced, eg. rain.

      For “normal” acceleration, grip should be perfectly adequate with 3mm or more of tread depth and weight transfer during braking helps front axle grip.

      In slippery conditions when it’s more common to lose grip when setting off or accelerating, a reduction of the accelerator pedal will cure this.

      Our experts would disagree that the rear wheel grip is more commonly required for the race track!

      This is obviously a debatable issue and we appreciate your input, John. It’s good to hear a second opinion. However in this case, our experts would have to disagree with you.

      Reply
      • I agree with John. It you lose grip in the front you lose steering and most of braking.. braking would be like trying to stop in snow with you e-brake only.. add to it another thought, a flat.. better on the front or rear. If you say front then you haven’t had a flat. So all the logic is correct the car is lighter in the rear, lighter need more tread in a lab or at higher speeds. Hydro planing.. when you hydro plane it’a all 4 wheels usually.. the rear fares a little better because it follows the groves dug by the front.. like following the groves of the car in front of you in the snow..

        Reply
    • Garden Mercedes

      I was literally having the same discussion with a greaser who was fitting a pair of tyres to my car at some big tyre warehouse, protyre. I said I wanted the new two on the front and he became super argumentitive and told me new should always be on the back and if I’ve heard anything different it’s bullshit lol. seemed like he almost wasn’t willing to do it for me after I was trying to explain to him why it’s better to have more grip on the front of a front wheel drive car for everyday driving, same as everything you’ve highlighted… But he would just refuse to even consider anything I’m saying…got them on the front in the end anyway, sometimes just easier to smile and nod rather than argue with these kinda people👍🏻

      Reply
  7. My car`s tyre is 175/65 R14. Front two tyres are very good in condition but rear two tyres are damaged. So, i brought 2 new tyres. But i did a mistake which i realized later that instead of 175/65 R14, i brought two 185/65 R14. There is no return policy as well.
    What should i do? Is it safe to install two new 185/65 R14 in rear?

    Reply
    • Tom Shattock

      Hi Vipin. It is not advisable to fit tyres of a size other than those recommended by the vehicle manufacturer and certainly not different sizes front and rear (unless the vehicle was designed to run different sizes of course).

      Reply
  8. Is it not, however, more common to get a puncture in the rears because of debris thrown up by the fronts, therefore making more sense to put the new tyres on the front? My last 3 punctures have been in the rears.

    Reply
    • Tom Shattock

      Hi Tim, we asked our experts and in a word; their response was no. The reason for fitting new tyres to the rear has nothing to do with punctures, it is about safety and best handling. Punctures generally result from random occurrences (that is excluding punctures as a result of tyre damage from hitting kerbs etc). Driving over debris with the front tyres is just as likely to cause a puncture in the front tyre as it is in the rear. In fact, the extra tread depth of a new tyre would usually mean the tyre is less likely to suffer a puncture due to the debris needing to penetrate further through the tyre before puncturing the airtight inner liner.

      Reply
  9. Anthony Lloyd

    I have three damaged tyres that have to be replaced on my Astra – two of them on the back. Following the “new on the rear” advice would result in my having a half worn with a new tyre on the front with different handling on left & right bends and extra wear on the diff.!? I have never put the best tyres on the rear.

    Reply
    • Digital Team

      Hi Anthony. We always recommend changing tyres in axle pairs and putting new tyres on the rear as our post explained. If you are concerned about the handling and fitment, as your comment suggests, please go to your nearest Kumho Dealer and they will help advise you. It’s hard for us to advise on this from a distance without the tyres in front of us and our guess is that you’d prefer them to be on your car! 🙂 Hope this helps.

      Reply
  10. Hi all, I’ve often considered this, and have always concluded by fitting new tyres to the front. My justification is that, assuming the new and old tyres are of the same compound (i.e. brand and type), they will perform equally in all circumstances except their ability to resist aquaplaning, the new tyres being more capable due to the increased tread depth. I think for the average driver, the risk of aquaplaning is only significant at speeds being traveled in a direction straight enough for the rear tyres to follow the path of the front tyres, for example hitting standing water on a motorway or straight section of an A-road. Conversely, the risk of aquaplaning is low, perhaps negligible, when the car is travelling around any curve tight enough to bring the rear wheels out of the path of the front wheels, as the speed is far less. Therefore, if the risk of aquaplaning is only significant when travelling in a straight line, I think it makes sense to fit new tyres to the front; this reduces the risk of aquaplaning to the front wheels due to the increased tread depth, and also reduces the risk of aquaplaning to the rear wheels as the rear tyres are following the path of the front tyres which have already dispersed any standing water to a level where the rear tyres can maintain contact with the road surface.
    Whilst I can see that, in theory, aqauplaning of the rear tyres is a worst situation than aquaplaning of the front tyres, in practice I don’t think this would happen during normal driving as the speeds are not high enough when the rear tyres are out of the path of the front tyres. However i am not confident I am correct, so have posted here so that an expert can reply back, as I would be very interested in their opinion. As you can see, I haven’t considered sudden tyre failure in my justifications. As an aside, I have experienced sudden oversteer (and a full 360 degree spin) as a result of fitting new tyres to the front wheels, however this was due to the new tyres having a different compound with more grip than the old rear tyres, and I won’t make that mistake again!

    Reply
    • Hi Simon. Thanks for the comments and points of view! Your mention of the 360 degree spin is exactly what we are referring to when recommending new tyres to the rear. Understeer is much more controllable by most people versus oversteer. Aquaplaning can happen with small amounts of water on the road and also decent tread depth. A lot is concerned with the speed in which the water is entered and crossed. Slowing down obviously lowers the risks and allows the tyres time to exit the water from the grooves but if the water is above the tread depth of a new tyre (and that’s only around 8mm, not really a deep puddle to be greater than that!) then aquaplaning can still occur if speed is involved too. However, if you aquaplane and go into a skid then the desired, if you can call it that, situation is one of understeer as it can hopefully be controlled easier and that’s where new rears could come into play. Hope this helps! Thanks.

      Reply
  11. What about the increased possibility of understeer with worn front tyres and new rears?
    This could cause the front axle to slide wide more readily than normal.

    Reply
    • Hi Daz – the rationale behind putting the new tyres on the rear is that understeer is easier to control than oversteer for the average driver. It’s the lesser of two evils. Added to this, if a tyre was to suffer a puncture or premature failure it is again preferable that this happens on the front axle because again it is more controllable. Many are now recommending this set-up which is also suggested by The AA. Hope this helps.

      Reply
  12. I have a motability Astra that had worn front tyres. The Franchise place I took it to simply renewed them and
    never mentioned about putting them on the rear.

    Reply
    • Digital Team

      Hi Jim – pop back to the franchise dealer and ask them to swap them around if you’re concerned as we’re sure they’d help. Thanks.

      Reply
    • Hi Jim – yes it does. You want the best traction on the rear of the car to try and eliminate oversteer. Thanks.

      Reply
  13. lionel lee

    I think there are many more factors to consider ! such as a puncture or tyre burst due to the advanced tyre wear?? another factor is loss of grip again due to advanced tyre wear to the front tyres ???

    Reply
    • Tom Shattock

      Hi Lionel! We agree that there are many factors but we would say that the key ones when looking at where to fit new tyres, discounting random acts such as punctures that are unpredictable, point us to recommend new tyres are fitted to the rear axle in pairs as the geometry of front wheel drive cars will benefit more from this set up than any other. Appreciate your input though and it’s an interesting and important topic!

      Reply
    • Cyclone Cyd

      Also, it is much much harder to control a moving car with a burst rear tyre than it is a front tyre. So it still makes sense to have your better tyres on the back as in a blowout situation (rare these days anyway) you can use the steering to control the vehicle whilst you come to a stop and you are much less likely to induce a spin.

      Reply
    • Tom Plant

      Ford Focus. I lost the back end in a corner, but managed to regain control with opposite lock. This was after following a garage’s advice and having new tyres on the front. I had them swapped fronts to rears and with the “old” tyres on the front it was much more stable. I’m not a reckless driver, I wasn’t cornering quickly, just the increased grip of new tyres at the front had a very negative impact on cornering stability with the back end sliding out (oversteer). I have to agree with putting rears to the front and new tyres at the rear.

      Reply
      • Hi Tom, glad you managed to regain control. Here’s to new tyres on the rear in most cases! Thanks.

        Reply

Click Here to leave a comment

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

city-lights-photos-bokeh-blur-road-car-night
Back
2016 Dodge Viper ACR