MisterX

Replaced the original Expedias with Potenza RE050A Pole Positions today. I thought the shocks or the bushings had deteriorated, but as it turns out it was the 14 year old rubber. The fronts still had 6/32nds left so they were far from shot.

Before running flat out does anyone know whether you have to heat cycle the tires?

rynberg

You should always heat cycle tires, even those for street use, IMO. I remember a high speed car mag test some years back (MT, I think), where their brand new Michelin Pilots delaminated on the banked sections of LV Speedway. The tires had not been heat cycled. Properly cycled tires did not show the problem.

Of course, last year showed us that Michelin tires don't seem to like banking....ouch!

MisterX

Ok, so I'll be sure not to run at Indy :-).

What's the proper way to cycle? Would a few short bursts to and from 110-ish work?

JConn2299

I've just purchased a set of Michelin Pilot Exalto PE2 tires for my car and I'm expecting great things from them. I'll be putting them on tomorrow.

Over time tires get harder because the molecules in them hook up and form longer chain molecules. These PE2 tires claim to have a life maximized compound that keeps the rubber soft through the life of the tire. (Some of the Bridgestones have a softer compound deeper in the tread layers and this softer rubber is exposed as the tire wears. A different method of accomplishing the same thing.)

As I understand it, there are chemicals that have to work their way out and through a new tire before it reaches its full effectiveness. It takes getting them up to operating temperature about half a dozen or so times to accomplish this. For this same reason, I've been told you should not put Armor All or any other protectant on the outside of new tires for the first 2 weeks. (There are some who say you should never use such stuff on tires. I'm going to choose to ignore them, but I'll follow the 2 week advice.)

JConn2299

From the Tire Rack website:


As participation in autocrossing, track days, driving schools and road racing continues to grow in popularity, the tire manufacturers have developed unique DOT legal competition tires which feature very sophisticated tread compounds. However just like other high performance parts, these tires will provide more consistent performance and last longer if they are properly broken-in.

The first time a competition tire is used is the most important. During that run, its tread compound is stretched, some of the weaker bonds between the rubber molecules will be broken (which generates some of the heat). If the tires are initially run too hard or too long, some of the stronger bonds will also be broken which will reduces the tire's grip and wear qualities. Running new tires through an easy heat cycle first, and allowing them to relax allows the rubber bonds to relink in a more uniform manner than they were originally manufactured. It actually makes them more consistent in strength and more resistant to losing their strength the next time they are used. An important heat cycling step is that after being brought up to temperature, the tires require a minimum of 24 to 48 hours to relax and reform the bonds between their rubber molecules.

Looking at the heat cycling system, it positions a mounted and inflated tire between rollers which apply pressure while the tire is rolled up to speed. It is very important to note that this allows heat to be generated as a result of deflecting (stretching) the tire within its normal operating range. There is no "artificial" heat added (no oven, no forced air, etc). Then they receive the stamp showing they are Tire Rack heat cycled.

Measuring the tread temperatures with a tire pyrometer we confirmed that in our controlled environment we were able to achieve appropriate and more consistent temperatures across the tire's tread without causing treadwear. All of these are significant improvements over heat cycling tires on our test track. And the 24 to 48 hour waiting period efficiently occurs while the tires are in transit to you. That means the tires are ready to use when they arrive!

The cost of heat cycling is $15 per tire. Avon, Hoosier, Kumho and Yokohama all recommend that their competition tires be "heat cycled" before being run in competition.

JConn2299

From Discount Tire Direct:

Heat Cycling

Leading tire manufacturers including BFGoodrich, Kumho, Nitto and Yokohama offer competition type tires that qualify as DOT legal for street use. Autocrossing, race days, driving schools and other racing venues demand this category of tire for maximum performance. But like any high performance part, these tires require careful break-in to achieve the full benefit of their construction.

A competition tire is built with a highly sophisticated tread compound, capable of sustaining traction throughout a much wider temperature range, but also extremely sensitive to the first heat cycle of its use. During this cycle, if controlled precisely, the tread compound stretches as it heats, breaking the weaker, shorter molecular bonds within the rubber. The benefit of this process is a tread compound that lasts longer and provides better traction. However, if the first cycle is not performed correctly, the tread may develop irregular compounding, leading to poor wear and inconsistent traction.

In the past, many racers tried to “heat cycle” their own tires with mixed results. Besides the inconsistency, there was the inconvenience of mounting and dismounting the tires before using them to race (after the first heat cycle, a competition tire must be rested 24 to 48 hours to reform the molecular bonds). In response to customer requests, Discount Tire Direct now offers heat cycling service.

The Discount Tire heat cycling system ensures consistent results by maintaining key conditions during the process: vertical scrubbing and “soft” temperature curve. Using rollers of proprietary design and placement, the system generates uniform heating and temperature build up throughout the tread (a condition not achievable on a vehicle due to camber) by rolling the tire and exerting vertical scrubbing force only. No lateral force is applied. A soft temperature curve, where the tire is gradually heated and then cooled over a specified time (ambient temperature must be consistent as well), is maintained and monitored during the cycle. In this way the entire tread is heat cycled uniformly throughout its depth and width.

At completion, the tire receives a Discount Tire Heat Cycle stamp. This service costs $15 per tire. All competition tire manufacturers recommend heat cycling service. In the time it takes to freight the tires, they have “rested” long enough to be race ready.

JConn2299

This is also from the Tire Rack website. It's for street tires:

Breaking In Your Tires

Tires are comprised of many layers of rubber, steel and fabric. Due to these different components, your new tires require a "break-in" period to ensure that they deliver their normal ride quality and maximum performance. As tires are cured, a "release lubricant" is applied to prevent them from sticking in their mold. Some of the lubricant stays on the surface of your tires, reducing traction until it is worn away. Five hundred miles of easy acceleration, cornering and braking will allow the mold release lubricant to wear off, allowing the other tire components to begin working together. It is also important to note that your old tires probably had very little tread depth remaining when you felt it was time to replace them. As any autocrosser or racer who has tread rubber shaved off of his tires will tell you "low tread depth tires respond quicker." Don't be surprised if your new tires are a little slower to respond (even if you use the exact same tire as before). Their new, full depth brings with it a little more tread squirm until they wear down.

NOTE: Be careful whenever you explore the capabilities of your new tires. Remember that every tire requires a break-in period for optimum performance.

MisterX

Good info, JConn. Thanks, man! I feel dumb for not searching given I had read the lastest Bridgestone/Michelin test on Tire Rack's site last week.

Aren't the Michelins you bought an all season tire? You must run your car through 3 or 4 seasons (or plan to). Me, dry weather is all it sees/has seen. I was somehat disappointed when I first glanced at the tread pattern of the RE050s- they've got 3 rain grooves running down the middle; I figure that just makes the traction that much less in dry cornering. Those tire companies sure take after F1 tire technology a little too literally these days, huh? Lateral grooves are the last thing a ultra-performance tire should have, IMO. Any kind of compromise just lessens the greatness of the original intent- I think that can be said for so many things in life.

JConn2299

No, I have the PE2. There are two types of Exalto tires, the All Season A/S, and the summer PE2. You can read an excellent review of the PE2 in the test section of the Tire Rack. That's what sold me on the tire.

I conducted a long and extensive search. I considered a number of tires. My first criterion was weight. I have the stock rims and I knew Mazda engineers went to a lot of trouble to specify a tire that weighed no more than 23 lbs. I really liked the S-03 and your tire, but I excluded them both on the grounds of weight.

I've also had tires long enough to see them harden over their lifetimes, lose their grip, get louder, and ride harder. I'm hoping this Michelin Life Maximized Adherence compounding will help prevent that. The Bridgestones are also very sophisticated in this regard.
The Michelin also claims to have a contact patch that enlarges in extreme corning.

Among the other tires I considered were the Toyo T/1R and the Yoko ES100. (The Michelin trumped the ES 100 in the Tire Rack testing. That made my final decision for me. And the Toyo got a bad review in comparison testing in one of the major car magazines.) I very seriously considered all the tires I mentioned. I think I made the right choice for me. We'll see.