So I just purchased a 2004 g35 sedan and I'm loving every minute of it. However, the only issue I seem to be experiencing is when I go to stop by pressing on the brake pedal. I feel that I get a rough stop and even some vibrations. This only happens at high speeds.

What do you think can be the issue?

One thing that I did notice however is that all the tires are different brands but unsure in size. Could this be the issue?

Thanks for any and all help!

 

Rough Stop doesn't explain what you're feeling, however I would check your front suspension and brakes. Every neighborhood has an independent brake/alignment shop that knows their job, find yours! Steering wheel shimmy happens when your rotors are warped, is that what you're experiencing? Having different brand tires on each corner might have negative driving results for sure! Begin by having your suspension checked out then check with www.thetirerack.com for a set of new tires...Good Luck & Enjoy the ride!
Gary

 

It is very possible the pads that are on the car are very cheap. They have overheated and just left uneven pad deposits on the rotors. Those uneven deposits are the cause of the vibration you're getting.

Get some pads that pair well with your driving style, try to salvage the rotors by getting some sand paper and cleaning them. Install the new pads and call it a day.

-Nick

 

Your rotors might be warped.