Mismatch tyre sizes on a 4x4

[Wurzeetoo]

Hoping somebody may be able to shed a little light on this. After many weeks of typical landrover issues and breakdowns I thought I’d finally sussed it enough to treat her to some new tyres as the rear general grabbers were shot. Nice guy in the tyre fitters said no need to change the front 2 budget tyres as nearly new just stick 2 insa turbo knobbly tyres on The back I asked him wouldn’t the 2 sizes matter on a discovery 2 td5 but he assured me it was fine. Drive away and the car felt hellbent in killing me trying to throw itself into every hedgerow. Taken it back today to be told the front wheels were wobbling like they are loose and not safe to drive until investigated on Friday so left it there. She drove to the garage as per normal. Question being has anyone had such a problem before? Would changing front tyres solve this? Hoping this isn’t the final nail to send her for scrap she’s a great workhorse! Thanks all

 

[Lincs Lass]

The insa,s are of road tyres only ,not road use ,,

 

[steveR]

Are the sizes front and rear the same?

Isn't the Disco permanant 4wd and would need same size all round to match gearing?

 

[Wurzeetoo]

No rears are a fair size bigger and yes d2 are permanent 4wd

 

[Lincs Lass]

It has thrown the steering geometry out of line ,that tyre fitter wants sacking

 

[Nearly]

The centre diff should sort it out but the abs will be all over the place.
4 the same is the only way.

 

[Wurzeetoo]

Thanks all so here’s to hoping getting 2 the same on the front should fix this. Agreed tyre fitter should have known this although I need to take some of the blame for being a gullible clueless numpty!

 

[Lincs Lass]

Putting two on the front the same size as the may cause more problems ,,bigger tyres require more turning space inside the wheel arch ,,unless you plan on fitting a lift kit to the suspension ,you need to get the rears back on the same size and design ,it was on

 

[steveR]

Thanks all so here’s to hoping getting 2 the same on the front should fix this. Agreed tyre fitter should have known this although I need to take some of the blame for being a gullible clueless numpty!

Not the case. They should have known this... they are the "experts".

 

[feilding]

Tyres should always be the same size front and back and changed all 4 the same time,

 

[Gordy1]

Not the case. They should have known this... they are the "experts".

Wholly agree!!!

 

[averageguy54]

Permanent 4WD MUST have all 4 tyres the same size and condition. Any other combination is an accident looking for a place to happen that will probably kill somebody.

 

[TripleSix]

Which pattern Insa Turbos are they?

 

[Wurzeetoo]

The car’s been left at the garage so not sure on the pattern

 

[milkloss]

No rears are a fair size bigger and yes d2 are permanent 4wd

the bigger rear tyres are constantly trying to push the fronts. This means on corners the front is always losing traction and jittery as hell, I don’t think the fitter was the sharpest tool in the box.

 

[Wurzeetoo]

Rang this morning and let him know the findings from here he was quite shocked and said he hadn’t heard this before. Problem being the fitter is the boss of the branch. Hopefully 2 new tyres being delivered this week on a plus I’ve yet again had a huge education on these issues! Thanks to all for your help

 

[Nearly]

D2 abs works on detecting a wheel going slower than the others on braking. It thinks the slow one has locked up and is skidding. It then slows down the other wheels until the slow one has 'caught up'.
In normal driving it will slow down any wheel going too fast, assuming it is spinning on wet surface etc.

Different wheel sizes make the wheel bearings travel at different speeds when driving on the level.
The abs has been throwing several fits by the sound of it.
Either your tyre fitter is daft or you are just pulling our chain.
Merry xmas.

 

[Wurzeetoo]

No chain pulling from me. Merry Christmas to you aswell

 

[holwellcourtfarm]

D2 abs works on detecting a wheel going slower than the others on braking. It thinks the slow one has locked up and is skidding. It then slows down the other wheels until the slow one has 'caught up'.
In normal driving it will slow down any wheel going too fast, assuming it is spinning on wet surface etc.

Different wheel sizes make the wheel bearings travel at different speeds when driving on the level.
The abs has been throwing several fits by the sound of it.
Either your tyre fitter is daft or you are just pulling our chain.
Merry xmas.

The wheel speed sensing on our old D2 was the most sensitive I've ever known. It would kick the ABS in when a wheel just dropped into a pothole as it sensed the speed change! Different size tyres must have had it doing cartwheels!

 

[steveR]

Permanent 4WD MUST have all 4 tyres the same size and condition. Any other combination is an accident looking for a place to happen that will probably kill somebody.

That was my understanding too...