Non star rated tyre circumference

[crash]

Hi guys,

So the time has come to treat the X5 to a full set of new tyres and have spent quite a bit of time researching on which brand to settle for.

I know there are the usual star rated brands that some say are a must if you don't want your car to implode within 3 miles of driving, but what i want to know especially from those that have gone the none star option,  have there been any noticeable issues?

The reason I am interested is every one that preaches the star branded tyres are a must is because they are perfectly matched when it comes to the circumference of the 255/50/19 fronts to the 285/45/19 backs, but after a little research i have found the following figures for non star rated tyres...

255/50/19 have a 2317.24mm circumference

285/45/19 have a 2321.95mm circumference

Which is a total difference of 4.71mm or 0.2%

Now i know this may vary between different brands but surely when talking of differences so low they wouldn't cause issues!

At the moment i have my eyes on a set of the Toyo Proxes ST's as they seem sensible money and wear pretty decently according to a large majority of reviews.

If any one has anything they can add to this i would be greatful before i take the plunge with the Toyo's.

Regards

Ash

[graemeX5]

Hi

there was a post going on about problems with diffs and gearboxes which appears to be linked to the tyre circumference and when the person changed the tyres on his car for a complete set the problem was solved

See link http://xdrivers.co.uk/forum/https://xdr ... ;topicseen

Hth

[philip600]

Hi, manufactures must have a reasonable allowance to account for wear rates of tyres ? My X has 20" staggered set up & as you've found the difference front to rear circumference is tiny but if you replace all 4 tyres, the fronts generally wear quicker than the rears anyway so the difference will increase. Tyres pressures can also make a big difference to the rolling radius & how many people never check their tyre pressures ?
It can cause problem on certain 4WD cars with no centre diff but the X5 has one. You will also find differences in the circumference of the same size tyres between manufactures as well,  one brand 315 35 20 will have a larger or smaller circumference than another brand. Certainly putting different makes front to rear or worse, on the same axle can cause issues but if you're fitting non star tyres of the same make all round you should have no problems. I ran Toyo ST's on mine until recently, they have stopped making 275 40 20 in these so I've had no choice but to fit a different make ( Hankook ) on the front, the rear Toyo's where fitted about the same time as the Toyo fronts but the fronts wore out quicker & I certainly wasn't going to replace the rears at the same time when they probably have another 15k miles left on them.
Phil.

[quote="crash"]
Hi guys,

So the time has come to treat the X5 to a full set of new tyres and have spent quite a bit of time researching on which brand to settle for.

I know there are the usual star rated brands that some say are a must if you don't want your car to implode within 3 miles of driving, but what i want to know especially from those that have gone the none star option,  have there been any noticeable issues?

The reason I am interested is every one that preaches the star branded tyres are a must is because they are perfectly matched when it comes to the circumference of the 255/50/19 fronts to the 285/45/19 backs, but after a little research i have found the following figures for non star rated tyres...

255/50/19 have a 2317.24mm circumference

285/45/19 have a 2321.95mm circumference

Which is a total difference of 4.71mm or 0.2%

Now i know this may vary between different brands but surely when talking of differences so low they wouldn't cause issues!

At the moment i have my eyes on a set of the Toyo Proxes ST's as they seem sensible money and wear pretty decently according to a large majority of reviews.

If any one has anything they can add to this i would be greatful before i take the plunge with the Toyo's.

Regards

Ash
[/quote]

[crash]

Thanks philip,

Very informative reply. It did cross my mind that even if the front and rear tyres had exactly the same circumference to start with, uneven wear would soon mean that any benefits would soon be lost.

I am sure even 0.5mm of extra wear on star rated front tyres would change the total circumference by more than the 0.2% difference the non star rated front and rear tyres have from new.

Regards

Ash