Rear tyre sizing and alignments

[DBA086]

Hi team

I am due to replace the ditch finders on my Coupe.

I am currently running the stock setup (225/45R17(F) and 245/40R17 (R)) on a lowered car and look to have some space in the rear.

A number of members of the US-centric forums have had good success with up sizing the rear to a 255/40R17, and it does seem to have some theoretical advantages (more grip, consistent profile with the fronts, etc).

Is anyone running that setup here? For what it’s worth I’ll be running Michelin Pilot Sport 4s (not to be confused with Pilot Sport 4 S’).

Finally, is there any dark art to having an alignment done with these cars? Appreciate that there will be some rust on much of the components and I have coilovers, but is this something that Kwik-Fit, Black Circle or similar places can reliably do?

Chur

[Dave P]

Old post with some size details,



https://www.z3mcoupe.com/forum/showthread.php?t=20074

[petecossie]

My comments on tyre sizes are in the thread that Dave attached on previous post. I've had Falken FK453 255/40 98Y R17 fitted to rear wheels my car for 7 years and still going strong. I had the older FK451 of the same size on my previous M Coupe, again no problems.
John Safe (ZZZEMMCO on here) put me onto them back in 2005 when I bought my first M Coupe, we talked about tyres and he said he did track days at the Ring etc and found them to have adequate performance/good value for money. So if it was good enough for him, it was good enough for me with the mileage that I do. Other makes of tyres may have great ultimate performance in some areas but you pays your money...….
Check some of your local BMW Indys to see what they can do in the way of alignment checks. If you gave your location, you maybe able to get recommendations from owners on here. Don't think Halfords etc will have the expertise you require, could be wrong. I would prefer to use an Indy myself.
One our local Indys up here in North East has just installed state of the art alignment equipment which a few of the BMWCCNE lads have used.