New tyres need to go on the rear?

[JumboBeef]

Have a look at this thread:

http://www.caravantalk.org.uk/topic/38108-tyre-tread-when-towing/

It has been stated that when only two new tyres are fitted to a 4x4, they must be fitted to the rear and not the front.  Any truth in this please?

(I've recently had two new tyres on the front of the Disco).

[V8MoneyPit]

It's to do with 4x4's fitted with viscous couplings. The fitting to the rear is not always correct though....

http://www.mud-club.com/forum/index.php/topic,79481.0.html

[JumboBeef]

Ah.  Is it all 4x4s or just Freelanders?

[V8MoneyPit]

All 4x4's that have a VCU.

I'm guessing most modern small 4x4's will have one fitted. The problem is something to do with tyre diameter differences screwing up the VCU. Beyond that, I don't know the details.

In something like a Defender, the centre differential takes care of the problem.

[JumboBeef]

OK, in the three years that I've owned my Disco, it has always had new tyres on the front and the older ones moved to the back.  However, when you consider the tyre pressures are 8ppsi higher at the rear, is a couple of mm of less tread going to make a difference?

[V8MoneyPit]

But you don't have a VCU anyway, so it makes no difference what end the new tyres go on.

[JumboBeef]

Er, don't I? *idiot smilie*

Which 4x4s do and which don't?

[MuddyMike]

New tyres should always go on the rear wheels for safety. Any car is more likely to go into an uncontrollable skid from the rear wheels loosing grip than the front, so its on the rear you need your best rubber.
See.
http://www.celtictyres.co.uk/front-rear.php

4WD issues are more to do with the greater rolling radius damaging systems.

Mike

[lurch_917]

New tyres should always go on the rear wheels for safety. Any car is more likely to go into an uncontrollable skid from the rear wheels loosing grip than the front, so its on the rear you need your best rubber.

poppy cock id rather have the rear end go than the front 5 years experiance on skidpans the rear is almost allways recoverable by technice but the front when that goes you have no stearing till youve got it back under control wich takes throtle control and you geused it stearing

[Llanigraham]

Lurch,
argue all you want, but the advice from the likes of RoSPA, IAM, the tyre companies and all the other experts is that for the majority of drivers it is better that way around, especially in vehicles where all or most of the drive is to the front wheels.
When a vehicle oversteers, eg, continues to plough forward no matter what steering input is used, then MOST drivers will instinctively take their foot off either the brake or accelerator, thus bringing "drive/control" back to the front wheels.

http://www.tyresafe.org/news-and-events/detail/motorists-get-their-tyres--back-to-front--/

http://www.celtictyres.co.uk/front-rear.php

http://www.klebertyres.co.uk/KleberUK/front/affich.jsp?codeRubrique=8032005184616&lang=EN

[V8MoneyPit]

When a vehicle oversteers, eg, continues to plough forward no matter what steering input is used, then MOST drivers will instinctively take their foot off either the brake or accelerator, thus bringing "drive/control" back to the front wheels.

That would be understeer then?  :P ;)

[Range Rover Blues]

Far far safer to have a car understeer than oversteer, especially if it's oversteer where only the back wheels let go.  However, if you fit new tyres on the back and old ones on the fornt then the front axle is already turning faster than the back, even before you go into a corner.

On the RRC with the viscous coupling, LR recomend you only fit tyres in 4s.  what I don't get is they don't recomend rotating the tyres at all :-k

Oh, and with a viscous centee diff you tend to find it prmotes oversteer because the diff biases the drive to the rear in corners.

[muddysteve]

and the look on peoples faces when you go round the outside of them on a roundabout side ways in a P38 is priceless  :-$


(it was a diesel spill, honest)

[carbore]

I still find that advice (on those links) confusing becuase I agree with most of the facts, but not the conclusions.

YES, The front tyres ware faster, esp on a front wheel drive, but thats becuase they do the most work, surley its best to have the "fittest" tyres on the wheels doing the most work?

YES Newsest tyres are "stronger" and whilst im surprised that a rear blowout is harder to deal with than a front, again as the fronts do more work, surley you are much much more likley to have an age related tyre failure on the font than the rear (unless the vehicle is laden)

Also they BRAKING, most of the braking of a car is done on the front wheels due to weight moving farwards when you slow creating more pressure on the fronts. again, surley its best to have the best grip where the most breaking force is applied?

YES. I agree that most drivers will deal with understeer better than oversteer, but id strongly suspect that as the frotns are coping with turning force and cornering force (working harder) then they are more likley to skid than the rears which are essentially just "following".

I think ill look for some more info on this, especially as the links provided all seemed to be quotign the same source (they were too similar in wording).

Not to argue, but becuase im genuinley confused.

[Range Rover Blues]

A lot of what you say is true, the front tyres do most of the work, given an even split of weight at least.

Yes they do the steering, the problem comes in the worst case, if you loose grip on the rear end you cannot keep it behind the front with any certainty.  Wheels that have stopped spinning have less grip than those that do and will eventually try to pass, if you loose the back end first it is very very hard to stop in a straight line whereas if you loose the front end you keep going in a straight line, in which case it is much harder to avoid obstacles and the stopping distance is increased considerably.

I guess it's the lesser of 2 evils.

[V8MoneyPit]

I would hazard a guess that most people who end up in a skid, do so through understeer after excessive braking in slippery conditions. I would further guess that those same people then simply lean harder and harder on the brakes even though the front is locked up.

Most incidents you tend to see in the winter involve cars ploughing straight on on ice.

So, like Carbore, I'm in two minds about the advice. But, in the situation I've mentioned, it is unlikely to make any difference which end the new tyres are on. The car would still do the same thing, with the possible exception of locking up slightly later if the front tyres had more tread.

[McGuire]

 The reason for the new tyres being fitted to the rear rather than the front is the same as for fitting radials to the rear and crossplies to the front (if mixing). New tyres (and radials) have more grip than used tyres (and crossplies) so, if fitted to the front, loss of traction at the rear WILL be far more sudden and uncontrollable than if at the rear with the used (or crossply)at the front.
 Loss of traction at the front tends to be noticed before the tyres actually let go, in that there is a feeling of vagueness through the steering which clearly tells you to back off or take corrective action. This is not the case at the rear.
 It's entirely a safety matter.

  And, just in case anyone wants to experiment with radials front, crossplies rear (I appreciate a lot of people now have never driven on crossplies!) I have one question - do you want flowers or donations sent? :D

[carbore]

I agree re crossply and radial, the TV said so back in the 70's

http://www.youtube.com/watch?v=c23MFIKiVdE

[Range Rover Blues]

I l earned recenlty that BTCC drivers preferred crossplies and kept using them untill their withdrawl in the mid 1980s.  Apparently they turn in much more sharply than radials whcih need to load up before they transmit the side load.

[carbore]

Interestingly, you can still buy them http://www.longstonetires.com/Crossply.php

Isnt the internet wonderful. (PS Im staying in a hotel and im so bored)

[Saffy]

Interestingly, you can still buy them http://www.longstonetires.com/Crossply.php

Isnt the internet wonderful. (PS Im staying in a hotel and im so bored)

No certain movies appearing on your bill then

[carbore]

I think I have a

[dxmedia]

I'd guess that the VCU on a landrover is of execptionally bad design, probably to the degree that if it was the states a class action would have been put in for a full recall and replacement.

Tyre wear makes no difference be it on the front or back of a permi 4x4.

Different tyre sizes will.


I know that the above is a floored statement, but...

If you drive down a straight road and have no centre diff and have different tyres on both the front and back, then there will be mechanical damage. For those 4x4's which have no centre diff (always locked - mosts Isuzu's, hiluxes, terranos...) if they are left in 4wd on tarmac and driven around it's not the centre diff which gives way, it's either the front diff or the hubs. The centre diff is not the weak point.

All a VCU is, is a viscous coupling. Hardly rocket science. They've been fitted in a number of applications for a long time, one very small step up from a 'normal' mechanical diff. When talking about the difference in tyre size due to wear compaired to the work which the centre diff does driving around town, tight turns, round abouts, parellel parking... it's insignificant.

The problem isn't putting tyres on a specific axle, it's the crap prone to failure unit which landrover fitted.

[Chastiser]

for me, new tyres would go on the front. not only is vehicle either rear wheel drive or 4 wheel drive. in addition, if you have mud tyres fitted that most likely have a soft compound, cornering on the road will show more wear to the side of the tread at the front, certainly does with mine. this would mean buying two tyres, fitting those to the front and rotating the fronts to the rear.

Mike

[V8MoneyPit]

My colleague at work had a garage refuse to fit tyres to the front of their Ka. They were going to charge him extra to swap the rears to the front and then fit the new ones on the rear, so he took the wheels there off the car and had them fit them.

[Manicminer]

My Toyota LC Colorado is more likely to loose the rear on corners in the damp than the front. Sideways grip just cease to be if over cooked. New tyres on the back and it's ok.