Hey I just noticed my rear tire cupping along with my front tire,is this from too much air or not enough?Shop tech put 40 psi in them and said that was optimal,what do you guys think? OH and I'm running metzeler's

My front stock tire (Bridgestone I think?) cupped real bad on the left side. I believe it's from a combination of too low air pressure and the design of the roads in my area (crowned center). I have switched to the ME880 Metzeler and run 40 in the front and 41 in the rear. Have about 6,000 miles on them and all looks OK so far. Still wearing faster on the left but no cupping.

BT

I run stock pressures, I think it's 36 front and rear unless traveling 2up, then I bump it up alittle. Incorrect balancing could cause cupping also.

Improper Alignment of the wheel could cause this as well. Everything lined up back there? BB

your mechanic is correct. If you go to the Metzler site you will find that they actuall recommend that you follow their pressure ratings not the manufacturer of the bike. i saw that today on their site. i believe it also said pressures were 41 front and 42 rear but, check to be sure.
Cupping can be caused by pressure issues and also by normal wear.

It's weird,my 06' has only 3000 miles,the wheels are custom chrome wheels and the metzlers have excellent tread left on them,now I'm wondering if all the vibration and grind I'm feeling is due to alignment or bearings.Once cupping has started theres no correcting it right?

Well , if it is a bearing issue or alignment , correcting the problem is better than letting it ride. Alignment is easy , just take a tape measure and see if the axle bolt lines up evenly with the swing arm pivot bolt on both sides. Bearing issues can be a little tougher to track down. But if you have a bearing going out , you Should have some sort of indications (weird noise , like howling/roaring , etc...) , jack the rear of the bike up and see if there is any play....shouldn't be.

If it is simply a tire pressure adjustment , make the adjustment , and ride. Here's to hoping. BB

Thanks bear,I'm gonna go through again today.I'll post what I find.

OK here we go,the rear wheel axle nut and swing arm pivot axle are exactly the same length on each side.On the jack rolling both wheels,there is no free roll,brake pads are riding front and back rotors causing no free roll.The brake pads are are not hitting at the same time on front dual rotors which might explain the front cupping,so the front brakes are against the rotors without brakes applied and are hitting the rotors uneven,could this be wheel balance,or the fact that dual brakes up front always have this problem from what I read.Now on to the back,here again we have the brake pads riding the rotor allowing no free roll,you can hear the pads on the brakes,but wheel adjustment is dead on.To me it seems that I may either have some bad alignment on the wheels themselves or we have a problem with the brakes alone.This could be costly at a shop.

The brakes are very close to the rotors normally. That being said you should still be able to free wheel the wheels. You may here some scuffing from the pads which is also normal but they should not be stopping the motion. Are your rotors blued or heavily scored at all?