Breaking in New Tires

[sweet97m3]

Hello to all. Heading towards my first track event in three weeks and just put a new set of Sumitomo HTR Zs on as the Dunlops were too dried out to go much farther. Should have done this last summer but...

Immediately noticed that the new tires were slick and seem to slide much more easily coming into and out of turns under acceleration. Now I'm thinking that I could have my hands full in a few weeks unless it is just a matter of breaking these tires in. Is there a rule-of-thumb on this? Have already put about 80 miles on them this weekend.

Thoughts are most welcome! Thanks!

[cstreit]

Well new tires (particularly streets) are typically greasy for the first 150 miles or so while the mold release compounds are worked out. R rated tires are almost the same, but require less time to "break in".

With new tires you typically want to heat cycle them which means bringing them slowly up to operating temperature then allowing them to cool for 24 hours off the car. Of course you need two sets to do this, so many people don't. However you must still bring them up to temp. slowly the first time to avoid blistering and peeling.

Often with new ones if you hammer then the first time out a thin layer of rubber will de-laminate from the tire making them feel greasy and unpredictable for a while. You'd see this if it were happening then, the surface of the tire will start peeling away...

[RaceProEngineer]

Sweet,

We have no first-hand knowledge of Sumis, but most street tires require some "scrubbing in" before they start to grip respectably. You have a couple of sensible options:

- Put a few extra pounds of air in each tire, find a large, empty (and debris-free) parking lot, and drive in tight enough circles for the tires to squeel or howl. Sustain your "howling" speed for 30 seconds to so, and then do the same in the reverse direction. DO NOT LOCK UP YOUR BRAKES DURING THIS EXERCISE. When done, simply stop your car in place, and examine each of the tires. They should be HOT to the touch, and have a very dark, dull finish across the width of the tread - kind of like a huge, black pencil eraser. They are now "scrubbed in."

- Or, wait until your track event. Mention to your instructor that you have new rubber on, and he/she will have you achieve the same result, but on the track. It will require only a lap or two.

Hope this helps.
Ed LoPresti

[sweet97m3]

Ed/Chris, actually this helps me quite a bit. I will try and scrub them up in the next week or so and will also mention same to the instructor just to be on the safe side. Thanks for the tips...great excuse to squeal the rubber a bit while rationalizing the whole exercise! Really can't wait to get out there.

[chrisp]

Put a couple hundred miles on them and you'll be fine. If you know someone with a gravel driveway go up and down that a couple of times. Street tires don't benefit from heat cycling so no need to worry about that.

[ozz]

Sweet -

I put a set of HTR Zs on last fall to get thru the last few tracks days of the year. I spent an early Sunday morning on the freeway hitting the on ramps and off ramps pretty aggressively thinking I was scrubbing them a little. Hell, if I didn't, at least I was having fun. I probably put about 80 miles or so on them this way. They sat for 3 days and then I went to the track. When I got the track they were greasy for the 2 morning sessions but after cooling over the lunch break, came out and felt a little better and got progressively better as the day/weekend went on. When they get warm, I think they are every bit as good as the Yoko-AVS intermediates that they replaced. Good luck....

[sweet97m3]

Thanks guys. Living on a gravel road and having the gravel drive I might be able to make some progress here. Sounds like that, another 100 miles or so and some scrubbing will do the trick. The Sumis were an excellent deal and the reviews on Tirerack.com were just about 100% positive so I'm glad to hear that they are working well for you.