Replaced runflats on my R56 Cooper S - results

Replaced runflats on my R56 Cooper S - results

Author
Discussion

nckr55

Original Poster:

236 posts

216 months

Monday 7th July 2014
quotequote all
I've just made the change from runflats to non-runflat tyres on my Cooper S, and thought I'd write it up here for anyone who is considering oing the same.

For context - I've had my '09 R56 Cooper S for a few months now, and it has been perfect for my needs. I only drive circa 7000 miles / year, with a mix of urban commuting / school run and weekend trips out of town.The Mini is ideal for this sort of driving, good fun and small around town and pokey enough to feel brisk on more open roads. It replaced an Audi S3 which I had for only 4-5 months, bought as a misguided attempt to replace a DSG Golf R32 with a manual & less thirsty car. The R32 had it's own attractions (primarily a multi-cylinder engine and my first paddle-shift), but I found both the Haldex-equipped cars frustrating for the same reasons. Firstly, they had performance I couldn't use enough of, often enough. Secondly, I found the Haldex frustrating; too often it wouldn't 'hook-up' as anticipated, leaving only terminal understeer. The Mini is far more agile and adjustable. Turn in, carrying a little too much speed and a lift tucks the nose in nicely; feels like it is pivoting around you. Good fun.

But what made it less fun was the skittish ride and grim tramlining that the run-flat 17s bring. I had put the car on a set of 16 inch ('Bridge') alloys and Bridgestone Blizzaks when I picked it up. The ride was a little spiky, but the tramlining (that I remembered from my test drive) was absent. Putting the 17 inch 'Crown' alloys that the car was sold with back on brought back the tramlining and made the ride even worse. Although the wincingly awful ride across some of Edinburgh's worst road surfaces (my school run / commute seemed to annoyingly traverse some of the most awful) was bad, it was more the tendency of the car to hop sidewaays if it encountered any imperfections mid-bend that was bothering me. I spent a lot of time looking at fitting 16 inch wheels & tyres, versus replacing the 17 inch tyres with non-runflats. In the end, the front Pirelli PZeros were getting close enough to the limit (circa 3mm left and horrid in standing water) to be enough of an excuse to change all 4 corners. The Dunlop SP01 on the back were nearly new (circa 7mm) and I figure selling these (and the fronts for a few quid if anyone wants them) should bring the total cost to not much more than simply replacing the two runflats. Well - that's how I explained it at home, anyway (man maths).

After a bit of reading up and shopping around, I settled on a set of Dunlop Sportmaxx RT in a 215/45R17 size. These (a) open up a wider range of tyres and (b) are between £10-20 cheaper, per corner, than the standard (205/45) size. I spoke to my insurer (Direct Line) before changing, in case they viewed the change as an 'enhancement' or 'modification'. I was told they didn't, when I was careful to explain the compatibility of the new size, and that it still met load / speed requirments. I was also slightly nervous that the fractional extra width (vs. 205/45R17) would persist the tramlining, and the extra rubber may eliminate any weight savings vs the runflats. But the overwhelming weight of anecdotal evidence suggested that the key difference would simply be moving away from runflats, so I took the plunge.

If you read Evo, you may reognise the Sportmaxx RT as what they chose to fit to replace the Kumho Ecsta trackday rubber on their R56 JCW GP2 and the skinny eco tyres on their GT86 - so I figured they would be decent. And their excellent wet weather performance makes them an attractive route to minimising the length of time the winters need to be on the car for. Best deal I found was using a local mobile tyre fitter (City Mobile Tyres, in Edinburgh - no affiliation) and was even cheaper than using Blackcircles / Mytyres and a local garage to fit. Plus I like giving business to local / self-employed people, in principle. Tyres were fitted and balanced at my house for £400 all-in.

First impressions were that the car was much smoother to drive. The tramlning has gone entirely, and grip levels seem not so much ''higher' as 'smoother to tranition'. The key is that the sideways skipping off bumps has gone, so the car feels much more composed in the corners. Ride for passengers is far better (it's still a Mini in relatively large wheels, which is never going to ride like a limo), but the sharp edges have been smoothed off a bit. My wife took the car out and returned gobsmacked at the transformation. With a couple of hundred miles under the tyres now over the weekend (including a trundle through to Glasgow and back, as-related well as some 'spirited' driving, to get a sense of the tyres when pressing on), I have to say it's the single best motoring few hundred quid I've ever spent.

If you are sitting on the fence about replaicing the runflats on an R56 - stop dithering and do it. It honestly makes the car so much nicer to drive it's scarcely believable. And if you are going that route, I would heartily recommend these Dunlops.

(As an aside, I weighed the ruflats that came off the car. The Pirellis came in at 8.6kg, with the Dunlops at 10kg each. Even allowing for the greater wear on the Pirellis, I found the difference surprising. Annoyingly, I forgot to weigh the new tyres).

Still need to address the issue of what happens if I actually get a puncture, of course. Will pick up a can of 'tyre goo' ASAP, and investigate the space-saver spare.

The only downside of this whole thing is the car - which previously felt like more power would be a Bad Thing - now feels as if it could comfortably take more. Side-effect of it being able to get it's power down more cleanly & smoothly, I suppose. Bit of a ramble, but hopefully helpful for anyone who is thinking about going the same route.

nckr55

Original Poster:

236 posts

216 months

Tuesday 8th July 2014
quotequote all
Tyre guy set them at 35 all round, and I upped them fractionally to 36 (37 was a bit hard, so backed off) before my run through to Glasgow on Sunday (3 up plus luggage on the way there, and travelling briskly on the way back). Haven't felt the need to change them back (based on the ride) yet.

Are you setting the rears softer to help the ride - or in pursuit of a touch of "roll oversteer"?

Incidentally, the Hankooks were looking like the tyre I was going to put on, initially, based on recommendations from a work colleague (runs them on various Subarus). I just happened to get a good deal on the RTs.

To the poster above - who prefers the sharpness / edginess of the runflats - I can understand that. It's a subjective preference. And the direct, twitchy, karty feel we what impressed me on my test drive. Just prefer the non-RFs on balance.

nckr55

Original Poster:

236 posts

216 months

Tuesday 8th July 2014
quotequote all
XL 91 on the Dunlops, I think (vs 84V non XL on the OEM runflats)