Bad Braking

[mic]

hey guys since I put the bigger wheels on my ute (295 on 12 inch rim) my abs has been playin up abit. when on the highway after about 5 klms the abs light, traction light and I think engine light comes on. on the street its ok no lights. but also noticed the brakes sometimes kinda dont work like the pedal is real hard. and sometimes will make a thud thud thud as the wheels go round. not sure if just the back or both. I put new fluid in bled it etc. no real difference, pads are sweet. any ideas appreciated.

[ratter]

is it ok with your old wheels on it, if so go back to your original wheels as you do not want/need to have any sort of braking issue.

the problem may be due to different tyre heights upsetting the computers

[mic]

thanx mate yeah that's what I suspected. the rear tyres are massive, they say 45 profile but visually look twice as big as the front. even though both f and b are 45 profile. old wheels are long gone, I may have to get appropriately sized rears to even out the profile.

[ratter]

the profile number is a percentage of the width, so a 295 45 will be 25 mm higher than a 245 45

[Adam]

Mick's right. That will be the problem. I've seen this happen to a car that got a flat tyre on a cruise. The spare was a lot smaller than the other 3 and it progressively made the car more dangerous as the various systems started to fail.

We put a correctly sized spare on and everything was back to normal.

[mic]

ah thanx mate

[Guest XR09]

How far can you go before the sensor start kicking in or cutting out ???

I have 19 x 275 x 30 on the rear. I want to go 35. But think it's not worth it as I do go out of spec, not that I have ever claimed in a car. But knowing my luck.

Not really worried about it. But if it would affect the way it brakes I think I will forget it

[Wenier]

Its not that the brakes are affected its the TC and DSC or any other system that uses wheel speeds that is affected. And those systems usually use the brakes to make changes so of course it then limits your brakes effectivness.

I wonder if you pulled the abs no.2 fuse if it would work normally and this should kill the ABS TC DSC etc, but still allow the speedo to work. But if you had an accident with fuse pulled your buggered.