strange drumming noise on my saab

[dalebrignall]

hi floks been on the saab forum and no response ,ive had a drumming noise comming from the front wheels of my saab ,one of the alloys had a bit of a flat spot from a pot hole .i moved the wheels from front to back and the noise is worse.also the tyres are now not the same make on the front . i cant feel any play in the barings they seem fine .i have had the wheels balanced loads of times .i am changing all the tyres this week for a decent make as im fed up with the noise of the cooper tyres.i know this is a expensive way of dealing with this ,i had a lower wish bone fitted this year so all the suspension bushes are good ,is there anything ive missed many thanks .

[andrew.searston]

have you checked wheel bearings??
could possible be out of shape tyres

[dalebrignall]

all sorted one of my tyres was out of shape car nice and quiet on its italian maragoni tyres and they have been filled with nitrogen,i think its to help prevent the leaks in the tyre,i know they use this in aircraft tyres and f1 but my saab wont be doing 180 mph,probally a gimick i did not ask for nitrogen in my tyres .

[bmcecosse]

There's no advantage in a road car.....and if you need to top the pressures - will you use nitrogen???

[drivewasher]

We occasionally get asked if we fill with nitrogen, we don't. As Bmcosse says unless your running F1 race cars its a bit pointless in my view. Nitrogen is used because its molecules are larger than oxygen molecules and can't pass (eventually) through the ever so slightly porus inner liner of a tubless tyre so they don't deflate over time. As the atmosphere that you pump into your tyres via a standard air compressor is about 78% nitrogen anyway so youv'e already got 78% nitrogen inflation as you replace natural permitation losses you just top up the lost oxygen (20%) ish. Of course when you get a puncture your back to square 1 either way.
There are other reasons why nitrogen is used but I was wagging school that day. It never ceases to amaze me ho customers want to instal F1 technology like nitrogen but never check engine oil or change filters things that really matter.

Sorry am I just getting OLD!!!!!