Hey guys, when I mounted my new tires, I noticed my brakes arent catching as they use to. My pedal also pulsates when I brake decently hard at higher speeds.

My tires are 275/35/19 rear and 225/40/18 front, is that causing this problem? My mechanic also said my front rotors are warped.. so im going to replace that as well. But im not too sure if my diameters for my tires are also playing a factor in my pulsating brake pedal. No VDC/ABS light comes on by the way, any help would be appreciated.

I also know that 19 rears and 18 fronts are suppose to be okay since Nismo 350z run this setup stock.

 

IF your rotors don't have a lot of miles on them they can be turned! Does your steering wheel jerk back and forth when applying the brakes? That's the major warning your rotors are warped. While the rotors are being turned/replaced check the pads on all four corners. Wheel/tire size in your case shouldn't effect your VDC although it's a little strange! See how if feels once your brake issues are solved...Gary

 

Misleading title.. meant ABS. My brakes pulsates when im braking from high speeds.. and no, my steering wheel doesn't jerk back and forth, but the pulsate is definitely there and its strong when im braking fast. I rather replace the rotors.. they're EBC.. I went with DBA rotors this time instead with hawk plus pads

 

What a great and smart move! Do not allow anyone installing your wheels to use an impact gun, that's 80% of the reason you have warped rotors! The other % is just poor quality. Make sure right after installing the Hawk pads you do the "Bed In Process!" (Search) Let us know if this solves the pulsating...Gary

 

I've always used a torque wrench on my wheels and the stock OEM rotors still warp just backing out of the driveway.

 

Your assumption is correct.

275/35/19 = 26.6"
225/40/18 = 25.1"

The difference is more than 3%, so the ABS is having issues. You need to change one or both tires to get the diameters more inline. The front tires seem a little small in diameter, so i'd prob change them out to a 235/45/18 which is 26.3" in diameter and will work better for the ABS. No clue how they will fit your wheels though as you didn't provide rim width

 

I am having a very similar issue...but this happens to me when I am going 60-70mph on a highway and corner around slights bends on the road...without hitting the brake my car pulsates and the slip flashed. Never happens around any bends unless I am going pretty fast...I have the brembo set up, and brakes and rotors are new with less than 1k miles on them.

Running 20X9 in the front on 245/35/20
20x10.5 in the rear on 285/30/20

Could this also be the ABS due to the diameters?

Side note--also doesn't happen all the time, so its hard for a shop to try and pin point this unless they see it happen.

 

There's only 0.02" difference in diameter front and rear. Not enough to make a difference really.

It sounds like it's an wheel speed issue, as if one wheel spins much faster than the other in a curve, but your tire diameters are close. Are those def the right tire sizes you posted?

 

Yes. Positive about the tire sizes.

I thing that I think could be a possibility is having 2 different brands...I have hankooks in the rear and toyo in the front. Although the brand are different, I made sure the low profile tread was as close as possible to being similar. Think this could be the cause?

 

^No, overall diameter is the only thing that matters regarding tires.

 

Wheels in front are 18x8.5 +22.
I was thinking about going 255/40/18 in front. I changed my front rotors today, the problem seemed to be gone in low speeds at least.. havent tried it going past 80 because i havent bedded in my brake pads yet

 

It's possible as manufacturers do have different specs for a standard size. Some are wider than others and taller, so you'll want to research the overall diameters of the two brands you have.

OD is all that matters. Basically the car wants to see the front and rear wheels turn at same speed. If the front wheels turn 100 times, the rear wheels need to turn 100 times during the same time period as well.

Most cars can tolerate about 3% before it throws the computer off. Keep in mind that during a turn, all 4 wheels spin at different speeds. The front OUTSIDE wheel will spin the most, while the rear INSIDE wheel will spin the least. That's why these problems sometimes show up during turns at higher speeds because the issue of wheel rotations being different is exaggerated during turning.

 

So would 275/35/19 and 235/45/18 work? Or should I run 255/40/18 fronts? My wheel size are 19x9.5 +22 and 18x8.5 +22

 

Just got home from driving a decent distance today. One thing I noticed after the new front rotors is that my braking power wasnt as good as prior, maybe because I still need to bed in my new pads and rotors. The pulsating on brakes only occurs when im stopping really suddenly or at a high speed. No ABS light or nothing comes on.. this happened right after I got my new wheels and tires btw.. so im pretty sure its my front tire diameter causing this. Any opinions?

 

What was your G's OEM setup op.. 19 rays or 18/17s