Freelander 1 tyres ????

ok now this is just a mad question as i dont know alot as yet
as to why if you change the front tyres for new ones
you have to put them on the back not the front.
now my problem is that i have 235 on the back and 225 on the front 17in alloy rims
and the front are now wearing out fast.
the rear ones r fine
landy was like this when i bought it and has been running with this set up
for a good while i think. and ive had no bad noise from the drive train.
??????? help ?????

basicly .. if the circumference of the front tyres are greater than that of the rears
the vcu will 'slip' and start stiffen or to lock up .. and cause constant tension / stress ( transmission 'wind-up )
in the ird / rear differential .. sooner or later one or both of those components will break ..
which in turn causes major stress to one's bank account ..

**there's a slight difference in ratio between the ird-front diff. .. and the rear diff.**
if the rear tyres are same circumference .. or often the case due to wear .. slightly larger than the fronts
then on a straight road there is none / very little vcu 'slip' .. so little or no stress to the 4wd tranny parts
be only when turning sharply / full lock .. that the vcu slips enough to cause temporary / minimal internal 'stiffness' ..
which one can feel on full lock in neutral ( clutch down ) ..
has more effect on full lock reverse for some reason .. like the brakes are being applied ..
( hence a good idea .. imho .. to take full lock or very tight corners .. gently on the go-pedal )

(all of the above assumes non slip dry road conditions
( in slippery conditions .. e.g. on snow .. the fronts slip .. causes the vcu to 'slip' internally
( which causes the vcu to lock up .. which sends engine torque drive to the rear wheels as well ..
( vcu 'lock up' happens almost instantly when the vcu fluid reaches a certain temperature ..
( the heat being generated by the shearing action of internal disc-blades type thingamajigs ..

LZ search 'vcu' .. be a zillion posts on the subject

** early hippos had a bigger ratio difference .. LR changed that at some point
not sure when the latter ratio diff came into effect .. post 2000 maybe ?
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think that's more or less right .. if not ..
am sure one of our LZ vcu / ird / rear diff / tyre experts will correct me ..

as for ..

is that i have 235 on the back and 225 on the front 17in alloy rims

Click to expand...

it's all to do with tyre 'circumference' .. ideally all 4 should be same make / model / size ..

i suppose if you need to replace the fronts only .. then stick the current rears on the front
( i think .. but not 100%sure .. from prev. lz posts .. that 235's will fit on fronts )
and get new 235's for the rears .. same make model etc ..

i'm guessing your current setup .. that the 235's have a larger sidewall anyways .. than the 225's .. i.e. without looking up tyre sizes / height aspects ..
so tyre circumference Probably larger at a guesstimate .. if same make / model

you'd best to have some 2nd and 3rd opinions on the above

It appears to have a TD4 F1. Have you checked that it is still 4WD? Jack 1 rear wheel up and see if you can turn it a complete revolution by hand easily.

If you can turn it, then your car is 2WD - in which case it doesn't matter what goes where any more than it does on a 'normal' car.

If it is 4WD - then I would say that you're lucky that it still is. As @hd3 says, all 4 wheels on a F1 have to basically be the same rolling circumference. Otherwise the VCU 'thinks' a wheel is slipping and if the difference is sufficient then it will tighten/lock causing wind up in the transmission which will blow your front (IRD) and/or rear diff. The good sound advice it to always run exactly the same make & model of tyres on all wheels and ensure they are all pumped to the same pressure. That really is the only advice I think you will get from this forum, I believe its universally accepted.

Its safest to replace in 4s, but that isn't practical often and as a minimum, replace in pairs. The advice from LR is to put new on the back and part worn on the front.

Although these 'rules' sound precise and exact - the practice is a bit more blurred. Obviously part worn are going to be 'smaller' than new - so you are not going to have 'basically the same' front & back, so why insist on same make/model? That's a valid point, but different makes, although having the same spec (eg 195/80R15) will have differing tread patterns and mouldings which will make them slightly different to each other - if you add part worn into that - it may equalise or magnify problems - so simlest to stick with the same make/model.

There's all sorts of other blurred info as well, such as a recent discussion on here checking differences between front/rear tyres. People measured their tyres from the ground to wheel hub and generally found the fronts were smaller -ie the weight of the engine squashes them, thus making them smaller. Why then, would you put even smaller (part worn) on the front?

While it looks like there's lots of reasons to argue the advice is rubbish - it will be at your peril if you chose to ignore it. There was thread run through here where a guy bought 4 new tyres that were 'exactly the same' make/model. After installed though the car drove bad and it was obviously having wind up issues. After being given the run around by the tyre co he noticed there was a slight difference in the tyre markings and the tyre manufacturer confirmed to him they were from different batches and slightly different design. After they got all 4 matching for him - the car was back to good.

bloody hell mate just buy the same size tyres
fort bow n stern,then all is good.

What profile are they?

Are they all 55?

or are you running 225/55 front and 235/50 rear?

225/55 theoretical rolling radius: 2134mm Front

235/50 theoretical rolling radius: 2094mm ~2% -ve change <-- very dangerous
235/55 theoretical rolling radius: 2168mm ~2% +ve change

235/55 are the safer option, at 2% +ve you might just get away with it (it might actually produce a close to neutral drive train if all tyres are in good nick!)

The "Measuring yer wheel fred" didn't get a lot of results but appears to show that with the same tyres all at the same 'normal' pressure of 30-32 PSI the fronts are 'squashed' by 2.9% (net 2.1% after IRD gearing). So with the rears being 2% bigger - that's within 'spec' of standards setup. However, if the fronts in this setup are squashed by 2.9% - then its going to be a net difference of 4.1& over 2.1% - so doubling the rate of IRD slip. I'd worry about that.

can't get my head around that .. surely tyre circumference remains pretty much the *same .. squashed by weight or not ..
* i.e. tyre material aint That elastic .. well not the tread material

or .. have i got that all wrong ?
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almost an hour later .. edited to add:
https://www.google.co.uk/?gws_rd=ssl#q=elastic+modulus+of+tyre+rubber
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https://www.google.co.uk/?gws_rd=ssl#q=elastic+modulus+of+tire+rubber

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yep they are 55's
i was worrying that they might b 2wide 4 the front
so im gona replace the front 4 235 55 17
and do as you say put em on back an the rear on front.
with xmas fast upon us,money is going on the man in red, and a white beard lol.
so all four is not a option.
wow thx guys for the info i never ever thought it was a big problem
i was gona just put the new ones back on front 225's
bloody so glad u guys put me right

"New on the back keeps your VCU slack"
"New on the front ££££££££££££££££££££££££