Help! Brakes Gone Hard

[s4rl]

Need help ASAP if it is a big issue
I had 235/40/18 on my car and the speedo reading was off by a mile
So today i changed the tyred to 245/45/18 and all is well
but when i hit the gas doing 70-80km/hr then step on the brakes the pedal felt solid

it seem like the higher the rev, the harder the brakes will be.

Can anyone help me on what the problem is????

[Seano350GT]

did you do it yourself or did a shop change it? Might have knocked something. Never heard of that happening before, have you checked your brake fluid?

[s4rl]

the tyre shop done it for me
it was all fine before until i changed it over.
do the skyline have any brake cailbraration of any sort?

[s4rl]

brake fluid is clean and to the max

[(Locky)]

with my old 180 once the vacuum line to the booster got kinked so the pedal was hard as a rock, but bearly braked

[s4rl]

all engine seem fine, this started to happen as soon as i changed the tyres of the car,
its not stiff all the time, only when the speed/revs are high

[sonicii]

if you lose vacuum in the brake booster, the pedal will feel hard and will require much more pedal force to slow down.

[scotty nm35]

Sounds like the non return valve in the booster line has failed. Nothing to do with putting tyres on it, unless the mechanics are retarded...

[s4rl]

how do i fix that if it is?
another booster?

[s4rl]

could anything happen to the brakes on the rear when they tried to put the wheel in?

[s4rl]

found the problem
the front tyre profile was lower than teh rears so it played up with my abs system/

changed them and all is well

[Seano350GT]

glad to hear it's sorted.