Mixed tyres front and rear

[MLCE WILSON]

Hi
up until this week I was running Dynapro AT's. 265/60/18's with 28000k's on them. Had a second tyre fail on the Aussie long weekend at Sofala. I havent been impresed with the Dynapro's and decided rather than buy 1 new replacement Dynapro I went for 2 x Cooper ST MAXX on the rear axle and retained Dynapro's on the front axle ( it was a $ decision as I couldnt afford 4 at this point in time but didnt want to blow money again on a Dynapro)

The Coppers despite being the same tyre size appear to have a larger diameter. Is there any issue with running slightly differnt diameter tyres on the front to rear.

I alway drive in 4WD

Also I regularly tow a 2.4t caravan - the LT construction of the coopers are much more suited to the load than the Dynapro's

Mark

[erad]

With my NW Pajero, I had 2 Hankook AT tyres fitted to the rear and two of the original Bridgestone Highway tyres on the front (until they wore out). Nominally the same size - 265/65/17. There were no drivability problems, but when I selected 4WD for towing my caravan, after a while, the 4 green lights would go out on the dash display and the orange CD light would come on. The distance before the lights came on varied according to hot or cold conditions - about 30 km hot and maybe 80 km cold. Mitsubishi dealer said they couldn't find anything wrong - I found it later when I bought a scan tool. Also, when I went to shift from any setting on the transfer case to another, it would take ages and some times not change at all unless I stopped the engine and then re-started it.


Finally, I wore out the Bridgestone tyres and got 2 more Hankook AT's. Problem gone. Transfer case shifts normally, no codes when towing my caravan. The codes that I was able to read said uneven tyre size (or something similar).

[RodMac]

Hi
up until this week I was running Dynapro AT's. 265/60/18's with 28000k's on them. Had a second tyre fail on the Aussie long weekend at Sofala. I havent been impresed with the Dynapro's and decided rather than buy 1 new replacement Dynapro I went for 2 x Cooper ST MAXX on the rear axle and retained Dynapro's on the front axle ( it was a $ decision as I couldnt afford 4 at this point in time but didnt want to blow money again on a Dynapro)

The Coppers despite being the same tyre size appear to have a larger diameter. Is there any issue with running slightly differnt diameter tyres on the front to rear.

I alway drive in 4WD

Also I regularly tow a 2.4t caravan - the LT construction of the coopers are much more suited to the load than the Dynapro's

Mark

Yes there is a problem running tyres of a different circumference (diameter) front to rear and even side to side.
'Wind up' of the transmission can occur when you engage the centre diff lock i.e. 4H 'C' and 4L'C'
The vehicle can come to a grinding halt.
You really need to have all tyres the same size.

[HeavyPizzaz]

Mixed tyres front and rear

I wouldn’t do it. Can’t do it basically on any AWD car. The Pajero user manual even says when replacing tyres, replace all 4 at once or something along those lines. And the implication (if it doesn’t explicitly say it) is that you use 4 identical brand/model tyres. My old Santa Fe manual said the same.


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[old Jack]

The ST Maxx is larger in diameter than most tyre's of the same size specifications so I definitely would not mix these with tyre's of different diameters.

As others have said it can cause problems particularly if using 4H as it puts extra load on the centre viscous diff, possible short and long term issue may arise and possible warranty implications if the car is still under warranty so unfortunately it is a purchase of another 3 tyre's so the spare also matches or you take the gamble.

OJ.

[Keithyv]

I've often thought what kind of fluid is in the viscous coupling and does it ever need replacing? Or is it all in the transfer case running on the same oil (I assume not)

[Keithyv]

Yes there is a problem running tyres of a different circumference (diameter) front to rear and even side to side.
'Wind up' of the transmission can occur when you engage the centre diff lock i.e. 4H 'C' and 4L'C'
The vehicle can come to a grinding halt.
You really need to have all tyres the same size.

Yeah but you wouldn't (shouldn't ) be engaging centre diff lock while on hard surfaces anyway so it should not be an issue.

I don't remember seeing any warnings in the manual about replacing all 4 tyres at once.
The coupling can vary its drive front to back so I can't see any way how you could get wind-up between front & back without the centre diff being locked..

[HeavyPizzaz]

I don't remember seeing any warnings in the manual about replacing all 4 tyres at once.

I’ll have a look tonight, 90% sure I’ve seen it




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[MLCE WILSON]

Thanks for all the replies.
It looks like a trip to the tyre place next week.
In the mean time I will stick to 2WD. Better to be safe than sorry

[HeavyPizzaz]

I knew I’d seen it somewhere. This is from MM Bulgaria by the looks of it but our manual is the same...




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[Keithyv]

There you go - I stand corrected.
Yes best to keep in 2WD then until all tyres are the same!

[MLCE WILSON]

Ordered the 3 ST Maxx - will be fitted next Wednesday. An expensive exercise but worthwhile in the long rune.
We are heading down to Narooma week after next with the van and intending to check out some of the state forest behind Bodalla and the old gold diggings.
It will give the tyres a work out.
thanks for all of the advice
cheers

[Mundy55]

Keeping all the tyres the same diameter is one of the reasons I use a 5 tyre rotation in case I need to use the spare some distance from home. There's also no point in having an unused but still degrading spare wheel because when you come to use it, its not fit for purpose. I've done 85k on my BFG KO2s and expect to get another 20k out of them. Whilst buying 5 tyres at once is a big outlay, its cheaper in the long run.

[aussieintas]

I have always run a 5 tyre rotation to even the wear rate on all the tyres and I get more kms from a set of 5. N oormally rotate every 7500kms when I do the service.

[Mundy55]

I have always run a 5 tyre rotation to even the wear rate on all the tyres and I get more kms from a set of 5. N oormally rotate every 7500kms when I do the service.

me too