Hopefully i can help..
Brake judder can in most cases be cause by issue with the brake discs/surface so to speak causing a pulsing of the brake pedal - tyres wouldnt really cause an issue like this - often cause for that can be an issue with the hydraulic side of the braking system causing the disc or discs to become warped and thus having warped discs and pressing on the brake pedal at speed you will feel that through the pedal/steering even..so the disc run out should be measured with a dial gauge to see if thats the case or not..another cause for judder can be due to whats termed as Disc Thickness Variation which in term means the outside and inside of your disc surfaces are no longer parallel, so your cars pads are pushed into the thinner areas and kicked back out by the thicker areas. The movement is transmitted back through the caliper pistons up brake fluid to the pedal and you feel the judder in the pedal..so really the next port of call really would be the disc's/surface condition wise..I do hope this helps..
Hi..there thank for your reply..
If the brake judder only happens under speed say..depending on the severity of the judder you get then it may not of been picked during brake testing.sometimes although depending how good their brake tester is can pick up that..if the warp is slight on which ever disc is at fault and can only really be felt at speed under braking - only proper measurments dial guage for run out would see that.thats something that would need to be checked out..one other reason could be lack of use.if a cars sits for period of time unused sometimes this can cause the surface of the disc to form a light surface rust as such.but wont form under the pads itself..so obviously when the car is used you will have the spot on the disc surface where the pads was against felt through the pedal.that too can in some case can cause judder.that might not be the case of yours but it would certainly be worth have the disc run out checked and see if indeed one of the disc is running out..I do hope this helps