Project 90: Tyres

In Part 1 we introduced you to Project 90, our 2009 BMW E90 335i, and went to work bringing the interior and exterior back to a near-new condition. The vehicle needed a bit of love from its previous life, but it was satisfying to show with just a bit of elbow grease and some simple detailing products what a difference you can make over a weekend at home. 

With the cosmedics out of the way, our attention could turn to what is most important to us – the mechanicals. Our 335i was purchased with reasonably low kilometres and full-service history. The factory service intervals are generally fine to adhere to for newer vehicles that lead an easy life, but we tend to recommend splitting the factory distances in half so that oil changes are performed at least once every 12,500 kilometres. The benefit of this type of preventative maintenance is hard to quantify, but engines will run cleaner and better for longer, seals and gaskets will not leak as frequently, and overall we see vehicles that are serviced more often have fewer issues (and cost less to run) over the longer term.

With this in mind, one of the first tasks was giving our 335i a tune-up service using BMW Genuine M TwinPower Turbo 0W40. This oil was designed specifically for turbocharged BMW M cars, like the F80 M3 and F10 M5, but can be used with great results in models fitted with the N54 and N55 motor such as the 135i and 335i. For owners of tuned vehicles or even those that simply enjoy a spirited drive from time-to-time, we highly recommend trying this oil in your vehicles. 

The more we drove the 335i in different circumstances, the more we got to know it. On the freeway, on long open (and smooth) country roads, the car was a real joy. The twin-turbo 3.0 litre straight-six motor slingshotted the car towards the horizon with impunity. It was quiet, comfortable, and it looked damn good. If you have to get across the state quickly, there are few other cars we would rather do it in. 

But on twisty roads – where BMWs traditionally outshone their competition – the steering didn’t carry the same sort of excitement that we’ve associated with BMWs of the past, and we felt the handling had some room for improvement too. While perfectly fine for most people in most driving scenarios, the relationship between the car’s tyres and its suspension seemed to deteriorate the more the 335i was pushed on rougher roads. The handling was a little inconsistent, with the front-end not providing as much grip or feedback as we expected, and the rear had a tendency to feel vague and floaty. As we mentioned in Part 1, the traction and stability controls made themselves known more than was necessary. 

Overall, we found it a hard car to steer with the throttle or drive out of corners smoothly. To understand this in the correct context, you have to know a little about the history of BMW around that time. You may recall that the E9x 3 Series was the first 3 Series that BMW fitted with run-flat tyres, as an alternative to carrying a spare tyre. This saved weight (improving fuel economy), as well as expanding the useable space in the boot, and saving owners the tiresome and dangerous task of swapping wheels by the side of the road. It was a case of implementing a new policy for the greater good. 

The type of run-flat tyres fitted to BMWs use a very stiff sidewall that doesn’t require air pressure to hold up the weight of the car. Most people aren’t fully aware, but the size and stiffness of a tyre’s sidewall (along with the tyre pressure) has a significant impact on both comfort and handling. The sidewall of a tyre is almost part of the suspension of the car, dealing with many of the imperceptible imperfections that we drive across every day. By fitting these run-flats, it meant engineers at BMW had to change the suspension by using extra soft rubber bushings and making the ride more pliant overall. It was a matter of compromise – trying to find the right balance of comfort, handling, and convenience. 

Interestingly though, BMW M cars like the E90 M3 were not fitted with run-flat tyres from the factory, and so the stiffer suspension was tuned to accommodate traditional high-performance tyres. For us, this means that we can borrow some of the engineering development performed by BMW’s M division and use that knowledge to make our E90 even better. But we are certainly under no illusions: fitting improved components does not make our 335i an M3, nor is that our aim.

So after the detail and the service, we got to work ordering a full set of Michelin Pilot Sport 4 tyres, which Michelin claims offer the same level of performance as the widely regarded Pilot Super Sports of the previous generation. (Michelin did not offer Sport 4S tyres in the E90’s size locally.) Initial impressions of our 335i M Sport on the PS4 tyres was positive. The ride was more compliant and the vehicle felt more natural on more challenging roads, but we still had work ahead to unwind some of BMW’s engineering decisions.

What we had done is fitted tyres with a soft sidewall to a car with soft suspension that was originally designed to alleviate the harshness that comes with run-flat tyres. We now had soft tyres, soft suspension, lots of tyre grip, and buckets of power at our disposal. The car would still have embarrassed most sports cars on the road, but we doubt it would have broken any Nurburgring records with that set-up. Overall, it was a good step in the right direction, and we now had some high-performance tyres that we could trust. 

Though there was nothing really terribly wrong with the handling of our E90 335i M Sport originally, we were executing a plan of ‘one step back, two steps forward’. We wanted to improve on the fantastic base that BMW had given us in the E90, without compromising on the day-to-day useability of the 335i. Be sure to follow us on Facebook to see the next instalment of Project 90.

 

New Mechanical Repairs: $1,385

New Non-Essentials: Nill 

Total Cost of Additions: $1,385
Total Cost To Date: $1,435

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