15 inch thoughts

As someone who has just fitted 205/55R15s to my 325i, I'm starting to think that 195/65R14 is the sweet spot for grunt vs grip.

On dry roads, the extra grip has greatly reduce throttle-steerability, so the car feels less agile and more understeery. Considering that the 15 inch basketweaves were an option for this model, I'm wondering if 25 years worth of tyre development means we're running more grip than BMW intended, so it has messed up the "synergy" of the car. Maybe the modern 14s (tyres were nothing special) are about the same grip as the 15 inch tyres were back in the mid 80s.

Also, the 205/55R15s (good luck finding the official 200/60R15 these days!!) give the car a slight lowering, and anything that brings that precarious M20 sump any closer to the road is a bad thing! And with the reduced sidewall (compared to 65 series for 14 inch), I can feel that the ride is a bit harsher. Maybe the old "bottlecaps" weren't so bad after all!

On the plus side, I'd expect braking distances to be shorter and hopefully the wet weather grip is better (my 14s weren't any good in the wet).

Quote
nomis3613
As someone who has just fitted 205/55R15s to my 325i, I'm starting to think that 195/65R14 is the sweet spot for grunt vs grip.

On dry roads, the extra grip has greatly reduce throttle-steerability, so the car feels less agile and more understeery. Considering that the 15 inch basketweaves were an option for this model, I'm wondering if 25 years worth of tyre development means we're running more grip than BMW intended, so it has messed up the "synergy" of the car. Maybe the modern 14s (tyres were nothing special) are about the same grip as the 15 inch tyres were back in the mid 80s.

Also, the 205/55R15s (good luck finding the official 200/60R15 these days!!) give the car a slight lowering, and anything that brings that precarious M20 sump any closer to the road is a bad thing! And with the reduced sidewall (compared to 65 series for 14 inch), I can feel that the ride is a bit harsher. Maybe the old "bottlecaps" weren't so bad after all!

On the plus side, I'd expect braking distances to be shorter and hopefully the wet weather grip is better (my 14s weren't any good in the wet).

In New York, (and on the net) 14 inch tires in our sizes have gone away it seems, so 15's sound like a good thing.

Rick

Those guys at Munich weren't stupid...
I'm not a fan of big wheels, specially if the car was not designed to have them in the firs place.
Unless you want to rebuild the suspension completely, stick with OEM wheel sizes!

JP