tire placement

[Mike Guenther]

When the NASCAR teams put on only two new tires they put them on one side, front & rear. Is that because they are saving time only jacking up one side of the car?

If I am going to put on only two new tires on my RX-7, am I better off putting them on the front, or on the rear, or on one side like the NASCAR teams?

My gut feeling is that the front is more important for steering but maybe the rear is more important for putting down the power. What is your experience with only two new tires?

[lateapex911]

It is really car and track dependant.

The Nextel cuppers do it at ovals to save time in pits and gain track position, while giving up little performance on the track in terms of lap times.

If you run an oval, then put em on the outside,

If not, then it's a car specific thing..

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Knestis]

You'll learn pretty quickly which side/end uses tires most quickly and, when you want to save time and only swap two tires, you'll know how to tackle it.

On the Golf, we ran the VIR 13 hours with the same tires on the back for the duration, swapping fronts every 3 hours or so. The car had an open diff so the outside front (left, since the track goes clockwise) wore because it was doing a lot of the work, and the inside got abused from spinning on the throttle.

It's relatively easy to lift the front of the Golf, from the subframe, straight in from under the bumper. It's relatively easy to pick up a side as well with one jack but lifting just the rear end is a PITA. That might factor into your planning.

I don't know Mazdas but you might discover that all four tires are doing about the same work and it comes down to the nature of the track, more than the car.

K

[Mike Guenther]

Jake & Kurt, thanks for your input. I'm not trying to save time on a pit stop. I have four tires with two weekends on them but one is flat spotted. I'll pitch that one. One I'm going to use with three older tires for the practice session next weekend at Daytona. That leaves me with the best two for the race and I'll buy two more. I just wanted some advise on what's the best positions for two new ones to go with the two best used ones. I've wondered about this before when I've only needed two new tires, but I haven't been sure what is best.

[lateapex911]

Well, first, make sure you properly heat cycle them..

Then, I would say that, not knowing which grn your car is, although if memory serves its the 1st gen, you should put them where they will balance the car better.

So, if your new tires are better than your old tires, put them on the end that doesn't stick as well. If you have issues with both ends at different parts of the track, then put them on the end that is costing you the most time. For example, if you are getting big understeer onto a long straight, fix that and you will be faster the whole way down the straight, and thusly, your lap times will be faster.

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[BUMPnGO]

My 2 cents worth would be to put the two fresh tires on the front. Reason: Turn #1. It takes a while to get whoa'd up there after you come off the main straight, as you'll see by the tires marks, and the extra grip helps. I'd put the worst tire on the right rear as it is pretty much along for the ride at Daytona. a track that is really not too bad on tire wear.

[dickita15]

unless you are trying to fix some balance problem you should be fixing some other way replace one side. a rear wheel drive car like the rx7 will not use up the tires on one end much faster than the other.
dick patullo
who often cycles tires on in pairs

[RacerBill]

Mike: I concur with Jake's response. I just had a pair of tires put on my street car and was told the same thing - put the best tires on the end where you need them most, front to reduce understeer, back to reduce oversteer.

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Bill Stevens
Mbr 103106
BnS Racing
83 ITA Shelby Dodge Charger

[Mike Guenther]

Thanks for the input, guys. Jake, this is my ITS car. My IT-7 is still under construction. The 2nd gen is not nearly as loose as the 1st gen. Understeer coming out of turn 6 onto NASCAR turn one has been a problem as well as the hard breaking coming down to turn one into the infield.

BUMPnGO, I know about that turn one. http://ITForum.ImprovedTouring.com/smile.gif Two years ago, the first time I had the ITS car out, I couldn't whoa it up for turn one on my first practice lap. I spent the whole practice session stuck in the soft wet infield watching everyone else have fun. I clenched my buttocks and white knuckled it for the rest of the weekend because it had used up tires and I couldn't afford to spend another dime.

Dickita, what kind of car are you driving? Tell me more about your two tire experience.

[BUMPnGO]

In 1992, I scrimped all year to go to this race (my first). The engine let go in the horseshoe just after leaving the pits on the 1st practice lap!!! Couldn't get the money back cuz I went on the Track. I guess if I was going to quit it woulda been that day.

[dickita15]

it is a ita rx7. there is such a huge difference with stick thru a tires life cycle, at least with hoosiers, that if you replace one end it will mask balance problems. when replacing right or left side tires only, the car drives the same it just goes a little faster.
dick

[jake7140]

Great thoughts guys, wish I would have asked before I swapped in two in the front (on a pretty well balanced 1st gen rx-7). Was going to new tires. But in qual found 1 or 2 were out of balance/bent. Kept 2 news on front figuring I could control the rear, but it eventually got out of control.... http://67.52.14.186/20040710RA-Lastlap.mpg

It was 9 laps spent chasing the rear-end until I ran out of track. Like the side/side idea.

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Steve
[email protected]
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</A><A HREF="http://www.geocities.com/elrss" TARGET=_blank>Elkhart Lake Racing_&_Sipping Society
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