2 new mini tyres - Front Or back??

[MarkyP72]

Hi,
Earlier this year I put 2 new tyres on the fronts of GF's mini, & only done few thousand miles on them so still in good condition. Rear Tyres now needed replacing, so I took it in to my usual tyre dealer (have know him for years) and asked him to put the new tyres on the front and switch the fronts to the rear. After collection I realised they've put the new ones on the rear! I questioned this to be told that this would be best to help with oversteer!! Is he pulling the wool over?? I'm probably being a bit picky as the old fronts are still good, but I just thought it's best to have new on the front? (The wheels that do all the accelerating/braking/steering) !
Cheers for any input!
Mark

[xr287]

Isn't the "theory" that in heavy rain they want you to have the tyres with the deepest tread on the rear so the first axle to aquaplane is the front not the rear and you understeer not oversteer.

Unless there is a massive difference in tread depth I'd always put the best on the front, they will wear quicker on fwd and even out anyway and the front does most of the braking work so you want plenty of tread for wet weather emergency stops!

[helix402]

New tyres should be fitted on the rear, the theory is: loss of front grip is easier to deal with than loss of rear grip.

[jackh707]

The petrol head inside us would put them new on the front for oversteer fun but... but in the aim of saftey new on the rear.

When I first had my MINI, the OEM run flats were dead so I put new T1rs on the front with the barely legal rubbish on the rear.
I spun it doing a U turn on the dual carriageway at the top of my road in the wet.
Put some T1rs on the back after that.

I'm not a noob either, I ride motorbikes everyday all year and regularly abuse a caterham on the road and track, quite open to oversteer when conditions allow, but it really caught me out.

[MX-5 Lazza]

Any decent tyre dealer will always put new tyres on the rear, no matter what the car is and which tyres are driven. Most will refuse to fitbthem to the front even if you ask them to. Under steer is easy for everyone to cope with, your natural reaction is to lift off which is exactly what will help. However, it takes experience to handle oversteer and lifting off might well see you going backwards into the scenery.

[MarkyP72]

Thanks for all your replies. It seems my tyre dealer has a valid point about putting new on the rears, but as always there's mixed views! I still think I would be happier with the new on the front so may get them switched over.
Cheers again
Mark

[jimmy156]

MX-5 Lazza said:

Any decent tyre dealer will always put new tyres on the rear, no matter what the car is and which tyres are driven. Most will refuse to fitbthem to the front even if you ask them to. Under steer is easy for everyone to cope with, your natural reaction is to lift off which is exactly what will help. However, it takes experience to handle oversteer and lifting off might well see you going backwards into the scenery.

Not my experience, every single time i have changed the tyres on any of my cars the tyre place has changed the ones i wanted them to and not moved anything around.

[MX-5 Lazza]

jimmy156 said:

MX-5 Lazza said:

Any decent tyre dealer will always put new tyres on the rear, no matter what the car is and which tyres are driven. Most will refuse to fitbthem to the front even if you ask them to. Under steer is easy for everyone to cope with, your natural reaction is to lift off which is exactly what will help. However, it takes experience to handle oversteer and lifting off might well see you going backwards into the scenery.

Not my experience, every single time i have changed the tyres on any of my cars the tyre place has changed the ones i wanted them to and not moved anything around.

You need to go to a better tyre dealer then

Seriously... try to find one single tyre or tyre dealer website that says it's ok to fit the new tyres on the front. I'll start you off:
http://www.theaa.com/motoring_advice/safety/car-ty...
http://www.michelin.co.uk/tyres/learn-share/care-g...
http://www.etyres.co.uk/flashmovies/new-tyres-rear...
http://www.tirerack.com/tires/tiretech/techpage.js...
http://www.etyres.co.uk/flashmovies/new-tyres-rear... <-- this one has a VBH video to make the point.

[MX-5 Lazza]

Correct the tail is fine but if you get rear aquaplaning while still having grip at the front you are going to spin, regardless of what you try to do. Did you watch the VBH video? It's not like she's a beginner when it comes to driving and she couldn't stop the car spinning so do you really think you could have "saved" it?

[MarkyP72]

MX-5 Lazza said:

You need to go to a better tyre dealer then

Seriously... try to find one single tyre or tyre dealer website that says it's ok to fit the new tyres on the front. I'll start you off:
http://www.theaa.com/motoring_advice/safety/car-ty...
http://www.michelin.co.uk/tyres/learn-share/care-g...
http://www.etyres.co.uk/flashmovies/new-tyres-rear...
http://www.tirerack.com/tires/tiretech/techpage.js...
http://www.etyres.co.uk/flashmovies/new-tyres-rear... <-- this one has a VBH video to make the point.

Wow. Thanks for these links. Watched the VBH video. I stand corrected and have learnt something. I'll be leaving the new on the rears.
Thanks again.

[Funk]

ash73 said:

Well if you put 8mm on the front and 2mm on the rear you're asking for trouble I swap mine over when they are part-worn, but they have to account for most people not bothering to do this.

Have a look at the VBH video; the tyres on the rear were still very much 'legal' (around 4mm of tread by the looks of it) but they aquaplaned nonetheless. I would also completely disagree with your comments about it being 'more instinctive' to correct a slide at the rear but once it's aquaplaning and moving sideways, they's very little you can do even if you're a skilled driver. Given the standard of driving I observe most of the time, the vast majority of drivers would have no clue what to do even once it's gone wrong. With understeer, people feel it through the steering wheel and their instinct is to back off - which in this case is the right thing to do and will resolve the understeer or aquaplaning as the car loses speed and the tyres regain grip.

It's very simple - new tyres on the rear if they're the same all-round. One of the things I don't like about BMWs is the staggered tyre sizes as it means I can often have new tyres on the front with part-worns on the rear. I don't think it would go any better with 215s on the back and 245s on the front!

[Funk]

ash73 said:

Funk said:

Have a look at the VBH video

I don't buy it, it looked like she made no effort to catch it and when she's got worn tyres up front she understeers right off the road, but that's ok apparently. Why was the test done on a roundabout?

A curve makes the point, sure. It'll happen in a straight line too. Many years ago I did a full day on car control including a skidpan session in a car on a hydraulic dolly. The instructor could life or lower individual corners to simulate aquaplaning or driving on ice for example. Even in a straight line it was very difficult (read 'nearly impossible') to correct the rear 'drifting away' during simulated aquaplaning even at moderate speed.

I guess you're thinking about oversteer invoked by adding power in a corner - easier to control, grip is only an 'ease of the throttle' away. In the scenarios we're talking about, grip isn't coming back until you've slowed significantly and even then it will come back suddenly, and with the wheels that are no longer facing in the direction of travel - a tank-slapper ensues. Even sorting out oversteer in a front-wheel-drive car isn't easy - you need to steer into the slide and hit the power which is the last thing you want to be doing if the rear's stepped out because it's floating.

One of the best things I've ever done, that course. Taught me more in 8 hours about car control than I'd learned in the previous 5 years since getting my licence. Highly recommended.

Edit: here are a couple of examples of how fast it can go wrong - in a straight line - when the rear aquaplanes:

https://www.youtube.com/watch?v=lCQYm0MDpxo&fe...

https://www.youtube.com/watch?v=oWKr-9tj-80&fe...

Edited by Funk on Thursday 19th December 00:46

[Funk]

ash73 said:

Interesting, but if a car aquaplanes in a straight line surely it's just an illusion of control, it's still heading for an accident; and is she actually aquaplaning on that roundabout? Or just reaching the limit of adhesion and allowing the car to rotate?

It would be interesting to see a comparison of braking distances too.

If the front aquaplanes in a straight line, you come off the power and keep the wheels straight - you'll be OK. The fronts also help by clearing a lot of water for the rears too. Most peoples' instincts when things go wrong is to back off, so in this case it works. If the first sign you have that something is wrong when the rear starts to slip sideways, you're pretty much screwed if it's because the tyres aren't in contact with the road any more. It also happens very quickly.

As for VBH 'actually aquaplaning', yes she clearly is - the limit of adhesion HAS been reached, the rears can no longer clear water as fast as the fronts can. If the issue wasn't aquaplaning, you'd see all four tyres slide at the same time and the whole car would slide to the left.

Braking is an interesting one and technically there shouldn't be much difference between the performance of a new vs. worn tyre under braking - it's not about clearing standing water out of the way as the car isn't aquaplaning. All tyres have grip and can displace the water in front of the tyre. It will come down to the ability of the rubber to grip under wet conditions rather than the depth of the tread.

Edited by Funk on Thursday 19th December 01:00

[Funk]

ash73 said:

Funk said:

If the issue wasn't aquaplaning, you'd see all four tyres slide at the same time and the whole car would slide to the left.

It's not just about clearing water, the compliance of the tread-depth gives the tyres their grip; so the worn rears let go first even in the dry. I can't tell what's actually happening in that video (and the others are RWD?)

In the dry, tread depth plays little part in generating grip (hence why slicks are the stickiest of all) Treadblocks are there solely to allow the tyre to move water out of the way in the wet. If it never rained, we could safely run slicks all day long - indeed, many people ran 'track-day' tyres like Toyo 888s which were about as close to slicks as it was possible to get whilst staying legal. They're now no longer able to be sold as the rules have changed and tyres must meet wet-weather standards. The M3 CSL was renowned for being lethal in the wet as it came on Michelin Cup tyres. IIRC, you had to sign a waiver when you bought the car saying you understood the risks of driving it on those tyres in the wet!

The reason why worn tyres seem to generate less grip even in the dry is more likely to be down to the age and quality of the rubber - worn tyres have been heat-cycled a lot and are no longer fresh. If you could buy 're-groovable' tyres for cars like you can for trucks, you'd find the grip felt the same as before you re-grooved them. Actually, if anything, they'd feel worse as you still have the same aged, worn rubber but now you've removed chunks of it to make new grooves and sipes.

Speaking of the CSL Cup tyres, here's a pic of them:



The original CSL Cups (on the left) have no lateral sipes on one side of the tyre (the outer edge) and very narrow central grooves - they're ste for shifting water basically. The Cup+ tyres have larger central grooves and as a result, less rubber on the road so less grip in the dry than the original Cups.

Edited by Funk on Thursday 19th December 01:28