Two Guys Rally

New Tires for the WRX [ May 8th, 2010 ] By:Charles Smith

After a short while of spirited driving new tires are required. That time has come for my WRX. Normally, if I were happy with the OEM tires I would gladly buy them again and I was happy with them. Except this time around I found out my OEMs (Bridgestone Potenza RE92s affiliate link) cost $250/ea. Thats pricier than most race tires! I loved them, but $1000 just for the rubber seems a bit high for not top of the line All Seasons.

The top rated All Seasons were the Continental ExtremeContact DWSs (affiliate link). Plus they were one of the lower cost ones! That may explain why when I tried to get them, they were on back order. Plus they have a neat looking tread. So I could have chosen to wait for them or grab some other All-Seasons.

So with the DWS on backorder, I went with the Bridgestone Potenza RE960AS Pole Positions (affiliate link). Decent performance at about $150/ea. That’s $100/ea savings compared to the OEMs that come with the WRX. So far I’m happy with my choice, and the reviews of the tire claim I’m going to stay happy with that choice for a while (30k-50k miles…more likely <30k the way I drive).

If I had some extra wheels (winter wheels) kicking around, I’d buy some specifically summer tires and some winter tires for only a little more than I paid for the all seasons. Switching wheels is a 10-15 minute job with a jack and jackstands. However, if theres a freak snow storm this summer, I’ll be able to drive in it.

Why WRC Cars Use Thin Snow Tires [ September 29th, 2008 ] By:Charles Smith

Watch this and look at how thin the tires/wheels are. Link for RSS.

In most cases the wider the tire the more traction is achievable. However in really snowy enviroments (ie Rally Sweden) thin tires can get more traction than wide ones. How? This works because the thin tire is putting a much higher pressure (PSI) onto the snow surface compared to the wide tire. This makes the snow compress and the tire/wheel sink down into the snow. Wouldn’t this just slow you down? Going straight…sure, but the problem in snow is stopping and turning, not going fast in a straight line. Snow builds up around the outside of the wheel and infront of it, so when the car needs to corner/stop it pushes against the snow. This increases the possible traction. This is the same concept as using ruts in motocross or with your car in mud. You can apply much greater cornering forces without losing traction.

There is yet another reason they use thin snow tires. The snowy rallies in the WRC are in areas that also develop a nice layer of ice under the snow. They use this ice to increase traction, mostly for straight line acceleration, and when I use acceleration that means in both directions (hint braking and throttle+). They use the ice by putting metal studs into the tire. The studs work just like cleats for grass sports. They dig into the ice (again because there is a ton of pressure applied to them thanks to the mass of the car) and allow force to be transmitted through them. But in order for the studs to get close to the ice the tire has to dig through the snow, and so that’s yet another reason thin snow tires are used in the WRC.

Mistakes Not To Make #2 [ September 3rd, 2008 ] By:Charles Smith

Mistakes in racing range from forgetting to secure a piece of paper in the cockpit which turns into an annoyance, to turning the wrong direction with the end result ending up in a tree. Consequences vary but some can be quite serious. One of which can end your race day is forgetting to properly inflate your tires. While this may seem like a no brainer to you, many people, who are not quite as vigilant as you, neglect their tires.

Tire pressure affects the only things that should be touching the ground on your car: the tires. Low pressure, while it may have increased traction it wears faster. High pressure might rob you of the traction you need and causes faster wear because there is a smaller contact patch. But there is a lot more that can go wrong:

• Debeading - Tire debeadings are a pretty bad event for your wheel. The tire’s bead becomes disconnected from the wheel and all the pressure is lost in one violent event. The tire then tends to get shredded up by the surface (especially at higher speeds) and comes off of the wheel. Steel/aluminum wheels don’t have so much traction on surfaces other than rails meant for them. Try to avoid this.
• Money Spent - As a privateer, spending money is on my mind when it comes to racing. Tires are expensive. But there are ways to make them last multiple events (especially in Rally), but improper inflation makes them wear way too fast for that.
• Crashes - While not separate from the money issue (cars cost even more than tires), expecting more traction than your over-inflated tires can offer will result in fighting the car. Fighting the car will fatigue you fast and increase your chances of making a silly mistake like understeering into a guardrail (or spectator! ONOES!)

So take some time to think about your tire pressures. If you know what you’re doing you might even run slightly lower or higher pressures than “ideal” side-to-side or front-to-back. If its a short enough race you might drop the pressure a tad to gain some traction but still last the race in tire wear. So dont forget to think about your tire pressures and the oh so important tire they’re related to. This even matters on your road car!

Gas Saving Tip #3 [ July 2nd, 2008 ] By:Charles Smith

Keep Your Tires Inflated

Low tire pressure increases your cars rolling resistance. Why? Because more rubber is in contact with the ground, and while this may generally be a good thing for racing, as we all know racing is not about fuel economy. Increased rolling resistance (which equates to traction) makes your engine work harder. Harder working engines consume more fuel so your MPG suffers. It is the same principle that makes road cyclists ride paper thin wheels and tires. So keep your tires inflated.

Keep your tire pressure around the factory recommended levels. However, if you over inflate your tire you may decrease the life of your tire while decreasing traction (what a loss). So keep an eye on your tire pressures! FYI the tire pressure in my WRX is currently around 36psi.

You should be able to find your factory levels stamped on a plate in one of your door frames. Combine that with the fact that most gas stations have free air for tires you really have no excuse to not keep your tires inflated. Happy hunting!