Z4: Odd Tread Wear, Original Tires

[zlightnin']

Although my expectations are low for UTQRs of 140 A A, I'm very disappointed in the wear performance of RE050A RFTs that were fitted to my Z4 Coupe 3.0Si.

I became concerned at around 11,500kms when both outer tread edges of the tires seemed to be wearing more than the inside. Checked the tire pressures and all four were at 30# instead of 33F/39R. Rookie mistake on me for not checking early and for relying on the dealer for tire pressures.

Pressure have been at 33F/39R since, and now at 15,500kms, I measured theses depths:
Fronts
Left, Outer/Middle/Inner Right, Inner/Middle/Outer
8/32in 8/32 8/32 7/32in 7/32 7/32

Rears
Left, Outer/Middle/Inner Right, Inner/Middle/Outer
4/32in 4/32 5/32 4/32in 3/32 3/32

The car has never been track or auto cross driven. My driving style (95% solo) is probably on the lower end of "spirited", usually 60-65kph in a 50, 90-110kph in an 80 or 90 zone, and driven probably around 20/80% on chipseal/normal asphalt surfaces. I have likely found one or two too many potholes this season:mad:. Lots of great backroads unfortunately they don't get patched quickly enough...

I have ordered an M mobility kit and thinking of switching to non-RFTs ContiSportContact3 (280 AA A) rating or Yokohama S.drive (300-AA-A).:dunno:

Are 4 wheel alignments for the 3.0Si relatively easy or should I consider only a BMW dealer for this?

Anyone have any comments or advice?
Best regards,
Jacques

[jsc]

Although my expectations are low for UTQRs of 140 A A, I'm very disappointed in the wear performance of RE050A RFTs that were fitted to my Z4 Coupe 3.0Si.

I became concerned at around 11,500kms when both outer tread edges of the tires seemed to be wearing more than the inside. Checked the tire pressures and all four were at 30# instead of 33F/39R. Rookie mistake on me for not checking early and for relying on the dealer for tire pressures.

Pressure have been at 33F/39R since, and now at 15,500kms, I measured theses depths:
Fronts
Left, Outer/Middle/Inner Right, Inner/Middle/Outer
8/32in 8/32 8/32 7/32in 7/32 7/32

Rears
Left, Outer/Middle/Inner Right, Inner/Middle/Outer
4/32in 4/32 5/32 4/32in 3/32 3/32

The car has never been track or auto cross driven. My driving style (95% solo) is probably on the lower end of "spirited", usually 60-65kph in a 50, 90-110kph in an 80 or 90 zone, and driven probably around 20/80% on chipseal/normal asphalt surfaces. I have likely found one or two too many potholes this season:mad:. Lots of great backroads unfortunately they don't get patched quickly enough...

I have ordered an M mobility kit and thinking of switching to non-RFTs ContiSportContact3 (280 AA A) rating or Yokohama S.drive (300-AA-A).:dunno:

Are 4 wheel alignments for the 3.0Si relatively easy or should I consider only a BMW dealer for this?

Anyone have any comments or advice?
Best regards,
Jacques
Fronts have about 60% of usable tread left and are worn evenly based on your measurements, rears have about 20% of usable tread and probably would have more likely 30 or 40% if the pressure had been correct from the beginning. Extrapolated front tyre life of about 35,000 to 40,000 is normal for this type of tyre for your type of driving.

You can't compare wear ratings across manufacturers, but I'd say the Yokohame S-drive tyres won't last any longer than the RE-050A tyres, based on the S-drive wear rate on my son's car, compared with the RE-050A RFT wear on our 325i.

You probably don't need a wheel alignment if you haven't hit any severe potholes and at 30psi you are quite likely to damage a rim before knocking out the alignment. If you do get one, though, make sure ballast is added during the alignment to the driver seat, passenger seat and trunk as per BMWs spec, otherwise you will end up with too much negative camber and too much toe-in, relative to the ideal spec.

[zlightnin']

Thanks for the reply jsc, and the ballast advice. I ordered the Conti3s this morning and booked an appointment with the local Mercedes dealer for the alignment (closest BWM dealer is 150kms). I'll ask if they are aware of the ballast requirements. Is this standard alignment procedure for German cars? Do you know what the ballast numbers are?

[jsc]

Thanks for the reply jsc, and the ballast advice. I ordered the Conti3s this morning and booked an appointment with the local Mercedes dealer for the alignment (closest BWM dealer is 150kms). I'll ask if they are aware of the ballast requirements. Is this standard alignment procedure for German cars? Do you know what the ballast numbers are?
For BMW sedans it is 68kg in each front seat 68kg in the middle of the back seat and 21kg in the trunk, so for the Z4 it could well be 68kg in each seat and 21kg in the trunk, but the trunk amount may be less. It also should have a full fuel tank and the ride height needs to be checked to see if it is in spec with the ballast in place, before the alignment is done.

I don't have the exact specs for the Z4, BMW dealers will have them, good alignment shops should have them too, but there isn't a Bentley manual for the Z4 yet (if ever), so this info isn't readily available to the public.

[CalRick]

I have about the same wear on my si coupe at almost 12,000 miles - a bit more than 5/32 on the rears, 7-8/32 on the fronts, fairly even across the tread. I have tracked it a couple times, and I keep the pressures on the low side on the street, 30-33psi or so.

[zlightnin']

I have about the same wear on my si coupe at almost 12,000 miles - a bit more than 5/32 on the rears, 7-8/32 on the fronts, fairly even across the tread. I have tracked it a couple times, and I keep the pressures on the low side on the street, 30-33psi or so.

Our mileage is pretty close - maybe the difference is that the road surfaces here are rougher:dunno: