Is this thread wear normal?

Head_The_Ball

BMW Series1 116i F20 5 door Hatchback.

Original factory fitted Bridgestone Potenza 5001 225/45 R 17 RFT (run flat tyres) on the rears. The same make of tyres are on the front but they are newer replacements as I had a non repairable puncture at about 13,000 miles on one front tyre and I had both fronts replaced.

The car has now done 16,500 miles and is about to turn 3 years old so I took it to BMW Snows of Portsmouth for a free of charge pre 3 year warranty expiry Vehicle Health Check and an MOT.

It passed the MOT with no issues or advisories. On collecting the car I was handed the paperwork and told there were no problems.

On reading the Vehicle Health Check paperwork at home I found that there were advisories for the rear tyres.

Both front tyres were measured as (Inner Middle Outer) 6.0 6.0 6.0 They have only done a few thousand miles.

Both rear tyres were measured as (Inner Middle Outer) 4.0 3.0 3.0 They have done 16,500 miles.

The middle and outer are wearing faster than the inner on both rear tyres.

Is that wear discrepancy normal and within tolerance or is there a possible tracking or other issue?

The car drives perfectly with no steering issues and no tendency to drift etc.

The paperwork is marked with 'call 1/4/18' against both tyre advisories. I presume that BMW Snows would have suggested immediate remedial work if it was required so I am just looking for reassurance that I have nothing to worry about and that I should just keep an eye on the wear on the tyres.

Thanks.

neilmcl

A 1mm difference across the full width isn't a big deal and doesn't suggest abnormal wear.

System

Head_The_Ball wrote: »

BMW Series1 116i F20 5 door Hatchback.

Both rear tyres were measured as (Inner Middle Outer) 4.0 3.0 3.0 They have done 16,500 miles.

The middle and outer are wearing faster than the inner on both rear tyres.

Is that wear discrepancy normal and within tolerance or is there a possible tracking or other issue?

Perfectly normal. It is due to negative camber that they put into the suspension geometry on the rear suspension so that the wheels lean slightly inwards towards the top. The reason for this is to improve handling on cornering. The more "sporty" the car the more you'll find the negative camber on the rear wheels.

Given what they've worn to now what I would be doing is swapping the back tyres to the front on each side. You want the most tread to be on the rear tyres anyway and also this will allow you to get the most mileage out of the tyres as on a rear wheel drive car the fronts will wear slower than the rears so when you put those rears on the front the rate of wear will slow down considerably.

Another point to note: Given how much camber there is on the rear of your car when the tyres get quite worn you can get feathering on the inside edge that creates almost unnoticeable stepping. That can create a droning noise as you increase speed which is exactly the same noise that a failing wheel bearing makes. So if you ever hear that noise from the rear, ask someone what it is and they say "wheel bearings", don't automatically assume it is and change the front tyres to the rear and see if it goes away first.

facade

Looks fine to me too.The backs are generally toed in a fair bit, as this drags the back end and makes the car more stable.
If you take it to a 4 wheel alignment centre, you could get it taken down to the limit of manufacturers tolerance, which will improve the wear slightly, at the expense of stability. I'd leave it alone.

Head_The_Ball

Tarambor wrote: »

Perfectly normal. It is due to negative camber that they put into the suspension geometry on the rear suspension so that the wheels lean slightly inwards towards the top. The reason for this is to improve handling on cornering. The more "sporty" the car the more you'll find the negative camber on the rear wheels.....

Would that not make the inner wear faster rather than slower than the middle and outer?

My inners are wearing more slowly.

Am I looking at it wrongly?

Head_The_Ball

Thanks everyone for your comments.

I'll give some thought to swapping front and rears.

I also have one original part worn front tyre that I kept when I had both fronts replaced last year when one front tyre picked up non repairable damage.

facade wrote: »

Looks fine to me too.The backs are generally toed in a fair bit, as this drags the back end and makes the car more stable.
If you take it to a 4 wheel alignment centre, you could get it taken down to the limit of manufacturers tolerance, which will improve the wear slightly, at the expense of stability. I'd leave it alone.

I agree. If it ain't broke, don't fix it. :beer: