Wheels/Tires
1. RFT for A/S
2. A/S for Max Performance Summer
3. Pirelli Pzero Nero for Sumitomo HTR Z III
4. Sportline CS.16
1. RFT for A/S
The Z4 was my first sports car, and I didn't fully realize how bad the stock runflats were until I swapped them out for some non-runflat all season tires. Everything improved - handling, ride comfort, stopping distances. The new tires also showed me how badly the car needed an alignment. With every new car you buy, change all the fluids and get an alignment!
With this tire-buying experience, I learned the importance of having a good tire shop. The guys there pushed me to the all seasons because of their price, and steered me away from max performance summer tires. I'll never put all seasons on a car again if it's driven in above-freezing temps. They also had difficulty getting the stock runflats off of the car due to their reinforced sidewalls and the low profile. My tire replacement experiences have been overwhelmingly negative... some have even gone so far as to drag the impact gun across the middle of the wheel from bolt to bolt (which shouldn't be used in the first place!! It should be a torque wrench!!), gouging the wheel. Be wary of cheap tire places. I've only been to two places that have been careful with my wheels when changing tires - a specific dealership and a shop back home. If you go cheap, expect some damage.
2. A/S for Max Performance Summer
Before I really knew anything I bought all season tires over max performance summer tires, at the shop's recommendation. I will never put all season tires on my car as long as the temperatures stay above freezing where I'm living. Max performance summer tires are the way to go if your climate allows it. In moderate temperatures, they are better in all weather conditions than all seasons. The primary difference is in the rubber compound used, which hardens and becomes less grippy as the temperatures fall. Otherwise, a max performance summer tire will always outperform an all season tire.
3. Pirelli Pzero Nero for Sumitomo HTR Z III
When my M blew a tire, the tire shop only had one brand in stock that would fit - Sumitomo HTR Z III. I was hesitant but didn't really have a choice. Frankly, I was impressed with the Sumitomos on the M because the stock Contis suck. Because I had perceived a noticeable increase in performance on the M, I replaced the worn out - down to the cords - Pirelli Pzeros with some Sumitomos. And again, the old tires were worn out, so of course a performance benefit was noted with the new tires. I have to hand it to the Pirellis, I should have never driven on them as long as I had. Knowing what I know now, the fact that they didn't have a catastrophic failure is impressive. Regardless, I had a very positive experience when switching to the Sumitomos, and the Sumis are some of the cheapest max performance summer tires available. They do tend to run a bit narrow, and the tires require a lot of balancing weights. If you're on a budget, they are a good way to go. Supposedly they don't perform well on the track because they get greasy when they heat up, but for daily driving with a few spirited runs now and then, they are great. Unfortunately the Michelins I replaced them with (on the M) absolutely amazed me, so the next set of tires I get will be Pilot Super Sports.
4. Sportline CS.16
Sportline CS.16 Review