Tire Counts?

[Sathersc]

Hey guys,

I'm the suspension team leader for Miami Universities new FSAE program. As a first year team, we have no idea how many sets of tires we need to plan on burning through. I was wondering if any other teams could give me some numbers on how many sets a team can go through between testing and the actual competition. Thanks!

[Sathersc]

Hey guys,

I'm the suspension team leader for Miami Universities new FSAE program. As a first year team, we have no idea how many sets of tires we need to plan on burning through. I was wondering if any other teams could give me some numbers on how many sets a team can go through between testing and the actual competition. Thanks!

[SeanM]

Well i'm not sure the exact number of tires you'll need but, i was told by one of the guys on the ryerson team that tires should be changed every 45 minutes while racing

[Denny Trimble]

We usually go through a set of soft (R25A) hoosiers in about 25 hours, longer if we don't care about performance and run them to 50% exposed cords.

We test on harder compound tires of the same construction, as they have the same characteristics as our competition tires, but last longer.

The handling will change with the softer tires, though, because the increased g's lead to more roll, pitch, load transfer, etc.

We've never gone through more than one set of tires at competition; they are usually 25-50% tread depth afterwards. Teams that run the Avon may have a different story to tell.

So, in summary, you need 1 to 20 sets of tires.

[james17]

We have had very good luck with buying used tires locally for testing. Top Formula Ford and Continental teams use hard compound Hoosiers and Goodyears for testing or qualifing and then toss them. We buy tires with about 75 to 90% life left for under $100 per SET. A set of used R45 Hoosiers will live for a very very long time (like months)

[Jeff The Pyro]

we went through the whole competition on a set of Avon A45's... and a whole lot more after competition from the same set.

[Wizard]

Sathersc,

An easy way to figure out how many tires you need is to start at your bare minimum and work from there.

You will need two sets of tires for competition (one dry, one wet). You don't need to purchase the wets before hand just have the reserved and have the $$$ to buy them when it does rain

You probably also want to purchase a set of used tires right away so you can use them for mock-up/assembly purposes and then your initial shake down of the car.

A set of R35 last almost forever. I know several teams including ours uses R35's to start. If you have time, testing on a set of R25's before competition will also help.

The amount of tires you will use will be based on your budget and amount of testing you want to perform. Tires are very important but if you don't have the budget you could techically get away with only purchasing 2 sets of tires.

[Mike Cook]

Denny, I don't think we ever got 25 hours out of a set of r25's, except maybe in the winter when you don't ever get them above 100 degrees. Those things don't last that long when it is 90+ degrees outside.

Sathersc,
like others have said, I would by one set of 25a's and one set of rain tires. I would make sure you have eight rims. Many first year teams barely make it to competition with a car that is put together (no offense) and if it looks like you are going to be cutting it close, one set of tires will be more than enough.

[Mike Cook]

Hey Denny, speaking of tires just saw your name in the latest Racecar Engineering....congrats/

[Sathersc]

Due to certain events well beyond our control, we're not actually entering untill the 2007 competition, so no worries about cutting it close. We are planning on doing as much testing/design revision as we possibly can though throughout the next year and a half though, so thanks for the info on about how long a set of tires will last! http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Denny Trimble]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mike Cook:
Denny, I don't think we ever got 25 hours out of a set of r25's, except maybe in the winter when you don't ever get them above 100 degrees. Those things don't last that long when it is 90+ degrees outside.
</div></BLOCKQUOTE>

Yeah, my figure is based on our average testing temperatures, 40-60F before competition. After competition, the R25A's get burnt up pretty quickly in the 80 degree weather.

And, after the first several heat cycles, the tires harden up noticeably.