Ok, just some advice that of course I didn't follow

I am 235/65 r17 all round, replaced 2 fronts that were worn with 2 identical size but different brand and tread style to rears, so running part worn identical rear tires on rear axle, and identical part worn on front axle-but rear to front different brand and treadwise (size seemed the same)

1. driving off after this change, felt like i was sort of either running noisy treads / tires or akin to driving on a cobbled road, after 5 mins noise was gone.
2. Then noticed at 1500rpm on inclines and at a low speed what can only be describe as shudder akin to going over a bit of non smooth tarmac.so was hard to tell at first, if this was the road surface or not until i found a smooth incline to test. The shudder was there.
3.Noticed it also in the low rev range as revved dropped down when I was coming to traffic lights or slow city driving.

This has been like this for the last 3 days, and only yesterday did i do some thorough testing to replicate groans shudders

SO today i replaced all 4 with identical tires tread make (on advice of many here thanks) did 1 hour of testing, normal driving, highway too, but especially up those inclines AND noise/shudder is gone.

So don't do what I did.....no idea what damage I caused but something was not right with non identical tires..the car just didnt like it. And apologies to all those that I annoyed with repeated posts, i tend to obsess alas.

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E53 X5 3.0d SUV prod.date 11/2004 eng.variant M57N Europe Right hand drive N