What causes this?

[Chipmunk222]

What would cause this on a front tire ? Hard to see but is raised and bumpy. Tire is a Bridgestone 120/70/17 with 31 lbs of pressure. (I can not find a recommended pressure on the tire, it may be there, but I'm struggling to find it)

Fairly new to street bikes, so any help would be greatly appreciated. Our roads here are a mix of curvy with some straightaways. (if that even makes a difference) Our driveway is gravel, but the bikes are always on pavement with the exception of the driveway.

 

[Bert-Aus]

The reccomended tyre pressure in my manual says 33psi for front and 36psi for rear -my stock tyres were Bridgestone BT21's.

As far as those bumps:wtfgun: get her checked out, ...could be forks:don'tknow:

 

[Fizzer6R]

the tire is now "cupped"

 

[Alex6]

I would not ride on those cupping tires. Replace them now.

 

[Chipmunk222]

Ok, so the tire is cupped, but what are the possible causes of this ?

 

[MichaelInVenice]

Ok, so the tire is cupped, but what are the possible causes of this ?

This is a pretty good description I found:

Cupping, which is more accurately described as scalloping, is a natural wear pattern on motorcycle tires and it will always follow the tread pattern. It is not a sign that you have bad suspension parts. It merely shows that your tire is indeed gripping the road when you make turns (thank you for that Mr. Tire!). This cupping develops within the side wear bands of a leaned motorcycle. The extreme forces that come in to play when the bike is leaned in a turn are what produce the effect and when the wear becomes sufficient, one will experience vibration and noise when one banks into a turn... The leading edge of the tread does not flex much as it grips the road and the rubber is scuffed off the tire in that area causing a depression. As the tire rotates, the pressure moves to the trailing edge of the tread pattern where the tread flexes more causing less scuffing so less material is ground off the tire. The more complex the tread pattern, the more complex the cupping pattern will be. The softer the compound of the tire, the sooner this cupping will develop. Radial tires are more prone to cupping than are bias ply because the compound of radials is softer... Low tire pressure will exacerbate this wear pattern and you will lose many serviceable miles by running low. Improper balance has nothing to do with cupping on a motorcycle tire. Improper balance will merely cause your bike to vibrate within certain specific speed ranges.

Motorcycle Tire Wear

In addition to low pressure, bad rebound on the front suspension can increase cupping on a front tire. Some tires are more prone to cupping than others, due to their design.

 

[Chipmunk222]

Ok, so if we are low on air by 2 lbs, could that make this much difference? These tires didn't look like this 2 days ago... I just don't understand how 100 miles could make this much difference.

 

[buzzbomb]

In my personal experience, I've found that two or three pounds difference in the recommended pressure, vs. actual causes significant wear and handling issues.

That being said, smooth tire to scalloped in 100 miles seems pretty crazy. I would expect that kind of wear, that fast if the pressure was seriously off. Perhaps it's time for a new pressure gauge?

I'm not being funny. I began mistrusting mine and bought a new one. The difference was several psi.

 

[Chipmunk222]

Yeah, that might be a good idea, usually we have one in each vehicle, so will hunt for a different one tomorrow and if that doesn't work, will go purchase another.
I just don't understand the tire wear, even our other bike, with the exact same tire is looking like it's going to do this as well. We are not "experienced/seasoned" riders and we are just learning the whole leaning thing, we have been out for the last two days and have ridden about 100 miles, if anything we are still on the grandma and grandpa side of the learning curve... no racing or heavy leaning... I don't think we've even gone over 50mph.... hoping it's just the air pressure.

 

[MichaelInVenice]

Are those new tires? New bike? How old is the rubber. Tires do degrade over time even if they're just sitting around. That's really odd for 100 miles, even if the pressure is low. I know guys who can do that in a day at the track, but they're pushing really, really hard on soft racing tires.

 

[redwing-2001]

Are those new tires? New bike? How old is the rubber. Tires do degrade over time even if they're just sitting around. That's really odd for 100 miles, even if the pressure is low. I know guys who can do that in a day at the track, but they're pushing really, really hard on soft racing tires.

hard to tell from a picture but it looks like you have a lot of tread left. The key is answering MichaelInVenice queasions above. You have an '09, are these original tires? Check the age of the tire (look on the sidewall for the DOT ID code; the last 4 digits are the week and year of manufacture). If the tire is more than 5 years old, time to replace. Check your pressure using 2 different gauges to make sure your gauges are accurate. Maybe you just didn't notice the cupping before your 100 mile trip. If you are certain that the cupping happened in the 100 mile trip, you may have a defective tire, then the only solution would be to replace it.

 

[Marthy]

Get new rubbers. Those tires came with your bike... a lot of those cup like that. Get a different brand you will be alright.

 

[Superzoom]

Well, from what you've said, I'm guessing that your pressure gauge is really, really inaccurate. If it's reading high, and you only had the tire inflated to 31 indicated, then it could be a lot lower than that. That would explain why both your bikes are doing the same thing.

You should get a copy of the manual and read the section on tire pressure (and read the whole manual ). And get a new tire gauge ASAP.

 

[Alex6]

Well, from what you've said, I'm guessing that your pressure gauge is really, really inaccurate. If it's reading high, and you only had the tire inflated to 31 indicated, then it could be a lot lower than that. That would explain why both your bikes are doing the same thing.

You should get a copy of the manual and read the section on tire pressure (and read the whole manual ). And get a new tire gauge ASAP.

+1: What he said.

 

[Chipmunk222]

My thoughts exactly and we are not riding hard. We have 2 Fz6r's, both have about the same mileage (around 5000) on them, purchased both used, one from a dealer and one from the original owner, both seem to be very well taken care of, mine might have been dropped at some point cause it has a few scratches and the ball on the clutch lever is flattened on the end.

I don't know the age of the tires but on both bikes they looked really good and had good tread, they did NOT look like this... just got them both inspected and I would figure the guy would have said that we were on the back end of our tires if he thought we needed them.

Don't know if it matters at all but neither my husband or myself weight more than 175 lbs. We ride together all the time, same roads, same speed etc.

I'm just baffled, i'm going to check the air pressure with a different gauge today and see if the reading is different and will update what I find.

Thanks everyone !

 

[JSP]

Same thing happened on my 6R on the stock tires. Was time to replace.

 

[Marthy]

Don't worry too much. A lot of those Bstone 021 did this. After reading few review we're not the only one I think... there's a reason why they came up with the 023.

Michelin pilot 2 or 3 are very popular. I preach for the Continental Conti-Motion. Been very please with them over time. a bit over 10K now on my set and I got a spare new rear in stock... I'll keep the old one on for a bit longer. The front one never cup and still look good for another run of 10K.

 

[DragonBlu]

The Bridgestone 021 was a dual compound tire with harder rubber center and softer rubber on the sides of the tread. It was supposed to corner good while giving the rider a longer lasting touring tire. Low air or lots of twisty road will show this wear pattern. They were a lower end Bridgestone and have been updated as some have mentioned. There are way better tires out there for our bikes. Happy riding!

 

[MichaelInVenice]

Oh yeah, forgot about the BT021s. They were horrible at things like this. Combine older rubber, maybe a bit of underinflation and a tire that's known for doing this in the first place and you can run into trouble pretty quick. Tires need to be replaced at five years no matter what the state of the tread. Some softer rubber compounds won't last that long...

 

[dart1963]

been so long since I was on stock tires, I almost forgot how bad those 021 were...