Tire break in or wear in. What changes?

[ledslinger]

I was talking with a friend about new tires being louder than after they are worn. I wondered if it was due to the projecting injection "[censored]" making noise util they wear off. He thought the tires undergo an internal change as they are used.

What really happens to a tire as it wears in?

It also seems that new tires lower fuel consumption but it seems to recover after a while. Is this common?

 

[friendly_jacek]

I was not aware about being loud. They are very slippery though until the surface grease wears off and a full imprint wears in.

I guess you can call tire thread wear in an internal change. Similar to new pads/rotors bedding in or rings/cylinder liners wearing in.

 

[daves87rs]

What kind of tire?

 

[Hokiefyd]

Yes, it's common for new tires to lower fuel economy initially. Even when you replace the old tires with the exact same tire, just new. This is because the rolling resistance is greater with new tires. More mass, more tread squirm, etc. In terms of rolling resistance, it's hard to go wrong with a bald tire!

I've also experienced more road noise in general as a tire ages. My suspicion is similar to the rolling resistance above. On a new tire, you have more mass at the tread area to dampen noise. There's also more rubber there to physically deform to a road imperfection before the tire belt "sees" it. I look at it like rolling a foam ball down a road vs. a hard metal drum, though that may not be an accurate way to look at it at all!

 

[Craig in Canada]

I've never heard a new tire louder than an old one - never.

New tires are slippery due to mold release compound and other surface factors. They need to be scuffed in.

New tires may spin on the wheels changing the balance because the mounting compound (some people just use soapy water) is still wet. Don't peel out or stomp on the brakes unnecessarily for at least a week after having tires mounted.

New tires have more tread depth and tread squirm than old tires. This enhances performance in standing water, but reduces crispness in dry conditions. Aged rubber is dried out, reducing wet grip.

Old tires can develop weird wear patterns from normal or abnormal vehicle characteristics. Things like heel/toe wear cause a lot of noise. Cupping creates uneven noise.

Beyond the surface scuffing new tires will break-in, with the belting adjusting to actual use and the compound being heat cycled. I've heard that it's most ideal to re-balance a set of tires after a couple of thousand kilometers although I've never had to do this myself.

 

[BuickGN]

I've had 4 sets of tires on the TL and without fail they all get louder as they get worn.

 

[fdcg27]

That has been my experience over the years.
It is a gradual thing, though.
You may not even notice just how much road noise your old tires are generating until you replace them.
It is then as though someone had turned off the "noise" switch.

 

[The Critic]

When I had a set of Cooper CS4 tires installed onto my friend's car, he said that the tires were very unresponsive and lacked a crisp steering response for the first few hundred miles.

 

[CapriRacer]

New vs used?

Short Term Changes:

Mold releases compound sometimes causes traction issues, but that last at most a few hundred miles.

The first few times a tire is heated up, the curing process may continue until it is stable. This is more an issue in racing than with street usage, but sometimes this may come out as fuel economy. This would probably last at most a thousand miles.

There are sometimes excessive amounts of antioxidants and oils, and they will migrate to the surface. This causes a discoloration, particularly with white sidewall tires. This may not appear until a thousand miles and will continue for another 6 months to a year. Cleaning the discoloration off is only a temporary fix until the tire stabilizes.

Long Term Changes:

Tires obviously wear. They may not wear evenly - and this sometimes results in noise. I am of the opinion that you can trace ALL tire realted noise generation that wasn't there in the beginning to alignment - keeping in mind that "In Spec" means "some distance away from optimum"

But if the tires wear evenly, then the tire generally gets quieter as time goies on. The less depth of the tread shortens the height of the thing vibrating, so it doesn't vibrate as much.

Less tread = better fuel economy. All other things being equal. new tires will consume more fuel than worn out tires.

Hydroplaning resistance goes down as the tread wears.

Dry traction? The problem here is that as rubber ages, it get less flexible. It is possible to feel this change as both dry and wet traction (non-hydroplaning), but it is also possible, you won't feel this at all.

Overall ride quality will deteriorate. Rubber has lots of built in damping and worn out tires have less rubber = poorer ride quality.

 

[Benzadmiral]

I'm about to have a new set of shoes mounted on my Buick this week. Lately it has seemed as if the ride quality has deteriorated a bit -- though, around here, it could also be that the roads have gone to pot (and pothole!). I'm looking forward to some improvement.