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      11-02-2011, 05:40 PM   #1
ss134
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Drives: ...a hard bargain...
Join Date: Feb 2009
Location: Germany/UK

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M3 very sensitive to tyre pressure.....

I'm sure most forum members check their tyre pressure on a regular basis but i would just like to share a quick experience. My car went in for a new
front tyre and alloy wheel (puncture which also resulted in rim damage) and i instructed the dealership to ensure that the car was aligned and the new wheel balanced etc etc....i also told them to ensure all tyres were inflated to 2.4 bar (CS3 E90 recommended pressures for less than 3 people in car).

I picked up the car and headed for the autobahn - the car felt strange, lane changes at speed did not feel as controlled as normal, the steering felt lighter and less communicative and the on/off ramps had to be taken slower than usual as the 'planted' mid corner feeling wasnt there. I owned another E90 m3 before this one so i have had plenty of seat time in these cars.

I drove home and started to think that the dealership had messed up the alignment or possibly the handling differences were down to the new tyre being not scrubbed in or different tread depth to the other 3 tyres (although my car is only 4 weeks old so my other tyres had done less than 1400 miles)
I drove the car for a few more days and decided that the reason could be that the temperature this week has plumeted - the road surface is colder and the CS3 are a summer tyre, makes sense that it will grip less and provide less feedback in colder temperatures.

After leaving specific instruction with the dealer to inflate the new tyre to 2.4 bar and check the others (he even wrote it on the work schedule and told me it had been done) i didnt even consider tyre pressures, surely a BMW garage can inflate 4 tyres to 2.4 bar.................wrong. Maybe their compressor was not calibrated but the result was that when cold all four tyres were inflated to over 2.5 bar. Once i had deflated the tyres down to 2.4 the car felt perfect again. I have my own tyre pressure gauge which i keep in the glovebox - garages and petrol stations are notorious for having
compressors which are not calibrated/read incorrectly.

Couldn't believe the difference -0.1 - 0.2 bar made to the feel of the car - especially at moderate/high speeds.

Check your pressures

My pressure gauge if youre interested: http://www.amazon.co.uk/gp/product/i...1&s=automotive
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2014 AW F80 M3 DCT
2011 AW E90 M3 DCT - Sold
2010 JZB E90 M3 DCT - Sold
2009 6MT E90 LCI 335i M -Sport - Sold

Last edited by ss134; 11-03-2011 at 06:09 PM.
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