Rumble between 60-70mph

Have have been snooping around this forum for a while & found it very informative.
I now have a problem which I can't find a reference to here.
I renewed the 2 front tyres a few months ago on my 53 plate 56K Freelander, I went for Pirellis. On leaving the tyre shop I had vibrations/rumble through the car at all speeds. I returned to the tyre shop & they re checked all the wheel balances & swapped the new tyres to the rear. I still had vibrations but after meticulously checking the pressures, which were rather high, the vibrations/rumble seemed to all but go but it has got steadily worse when travelling between 60 - 70 mph. Once over this speed it goes & below the car feels great.
I put the car into a local indy who had the prop shaft sent to an engineering company who re-newed the rear bearing. It has not solved the problem. I've now been advised that it may be a worn Viscous Coupling!
Having looked through this forum I haven't found any relationship between this 60-70 mph vibration/rumble & the VCU.
Could it be as simple as different makes of tyres front & rear? (The Michelins which are now on the front are the original rear tyres).
Any advice will be appreciated

Hi,

I doubt it will be your vcu, although it could be the vcu bearings.
Even this is doubtful as they normally vibrate all the time when they are goosed.
If all was ok before the tyre change then you would have to assume it would be the new tyres.
New tyres should always go on the rear as running larger tyres on the front can knacker your drivetrain.
I would check the rolling circumference of the new and the old tyres to check they are not massivley different, as even though they may be the same size/width etc different brands can vary hugely in size.

Just before my IRD went bang I had a knocking/vibrating at 60-70 mph, I has just fitted 2 x bridgestone dueller hp sports to motor. They went on the fronts but were quickly swooped to the rears when I had time. After getting the car up on a ramp me and a service tech at work checked it over and found the lower engine tie bush was knackered, I was skint at the time (moving house £££) and so waited another four weeks until I bought the part, the day I got the part in the post I drove the car to work in the morning and 400 meters down the road on a roundabout the IRD went bang, had the car recovered to work, diagnosis by the most knowledgeable guy there (ex landrover mechanic) was tyres, lower engine mount, VCU and drivers side driveshaft had all contributed to the IRD Failing. Check the gaitors on your driveshafts, engine mount bushes, if possible get another two matching new tyres. Not always a viable option I know but I learnt the hard way and will always change 4x4 tyres in sets of 4 from now on.

Try it with the prop removed, if it still the same then that eliminates tyre sizes, prop, VCU etc so then look at front driveshafts.....

had similar problem when changing two front tyres to Michelin latitudes rears Michelin synchro's had really bad vibration 60 to 70 e-mailed Michelin no reply swopped front with rear still there so replaced rears to same Michelin latitudes problem solve must assume that the latitudes have different diameter to synchro's (one of my first posts)
still got the two synchro's and my spares a synchro hate wasting perfectly good tyres

Problem solved for any one in the future searching for the same problem.....tyres!!!
2 new Pirellis on the front to match the rear, sorted!!!

Hiya.......for gods sake have identical tyres front and rear otherwide you are in for big trouble........this happed to me.........i had vibrations...these all stopped when new set of identical tyres were fitted. Glad you have done this ......... next I suggest when you can afford it get a recon VCU........ if you have done over 60-70k or the truck is over 7 years old...... Good luck ........... this all happened to me I now have an impending bill of a grand for a replacement IRD .......... my truck is begginig to rumble...oh dear...ulp

just go my freelander it has 3 diffrent tyres on it lol

I note that Phil says his tyre pressures were a bit high. High pressure on the rear tyres can cause the tyres to develop flat spots (no idea why but it happened to me on a new S Reg). If your tyres are causing a rumble this could be the reason. Once I lowered the pressure to the manufacturer's recommendation (revised - the original specification was wrong and a new page was issued to the handbook) and fitted new tyres I never had any further problems.

Similar problem, rumble at 50+ but only when power on, if I lift off and coast it goes, then power back on and it's back again. Feels really bad but does not happen all the time. ???