tire sizes f/r ?

[rickjohnson356]

The rules specify that we use FF tires for our FST cars. And, the specific sizes are part of the rules. From the GCR:
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2. Tires shall be Formula Ford slicks in standard front and rear sizes and using a hard compound. The Region, Division and/or racingseries sanctioning the races shall specify which manufacturer or manufacturer’s tires meeting this general description shall be permitted. Regional, Divisional and/or Race Series Tire Options:

1. Option 1. The spec tire manufacture for Formula First shall be Hoosier Tire. Front tires shall be #43130 20.0”x 6.0” – 13" R60 or R60A compound. Rear tires shall be #43302 22.5”x7.5”– 13” R60 compound or #43307 22.5” x 7.2” x 13” R60A compound.

2. Option 2. The spec tire manufacture for Formula First shall be Goodyear Tire. Front tires shall be #807-366-068 3321 20.0”x 6.0” – 13” R600 compound. Rear tires shall be #870-274-068 2015 22.5”x 7.5”– 13” R600 compound.

3. Option 3. The spec tire manufacture for Formula First shall be American Racer Tire. Front tires shall be 20.0”x 6.0” – 13” 133 compound. Rear tires shall be # 22.5”x 7.5”– 13” 133 compound.

4. Inter divisional races or special events may choose to allow more than one tire option by listing the options allowed for said event in the event supplemental regulations.

3. Any tires (brand, size, tread or construction) fitting the 13 x 6 rimsmay be used when the Chief Steward declares a rain race.
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There is a trend in the faster FF racers to use fronts on the back end instead of the wider standard FF rears. See the discussion on the Sprints in the FF section for reference.

It seems to me that this might be something to consider as an option for us in the 2010 race season.

Has anyone tested using FF fronts on the rear? With our reduced HP. it might be a better option for some (or all) tracks.

Also, using the same tire on all four corners would reduce the number of spares needed to have at the track, I know we should replace in pairs, but if one tire becomes unusable, we could use one of our 'second set' of tires as a replacement in an emergency. This would also potentially reduce the overall tire expenses for the season.

I would be interested in everyone's opinions on this topic.

TIA

[dc]

I won't speak for the FST rulemakers, but I think that more tire options and sizes might go against the spirit of the class. Yes, one tire for front and rear in theory is a good idea, but I am pretty sure that most of the FF guys are not using the same skinnies tire on both the front and rear. The whole tire rotating front to back goes out the window when that's the case.

For one, I appreciate one spec set of tires, and leave it at that. The Hoosier R60s in FST in the standard cantilever FF sizes seem to be working out very well across the board.



I'm sure Bill can expound more on the thought of small rears, but I do believe there was a reason they got away from that type of tire (FV) in the first place.

[problemchild]

Its not a bad idea.

The biggest problem would be that rear ride height is only adjustable by moving the height of the tranny in the chassis ... which usually is non-adjustable.

So, people building new cars could adjust that when building .... but people with existing cars (or converting FVs) would have issues.

The reliability of our current rpm range would also change.

We don't need the cantilever tires .... but we do need the current tire height.

Cheers!

[sracing]

I'm sure Bill can expound more on the thought of small rears, but I do believe there was a reason they got away from that type of tire (FV) in the first place.

Yep. It's the final drive ratio. We need the tire height that is listed in the rules to keep our RPM range where it's at. We don't have a quick change box.

[problemchild]

Before I drove on them, I thought the tire choice was peculiar and not the direction that I would have chosen.
Four years later, the Hoosier 60A tires that we are using, are the best thing about formula FST. I have won races and set lap records on tires that were approaching 20 cycles. I have used 3 front tires for every 2 rears .... so the wear is quite uniform. The extra front wear is caused by beating on the LF at certain tracks.
Anybody that has enjoyed the thrill of buying race tires will be delighted with the FST experience of not buying race tires.
Cheers!

[Bill Bonow]

Rick,

At the moment, we are using "off the shelf" 22.5" diameter rear CFF tires. As we continue to grow, we can go to tires companies (like Hoosier) and ask for a narrower and taller rear tire. Using fronts on the rears would yield not enough gearing / out of rev conditions at just about every track. Once we get a few more cars racing, I think tire companies (like Hoosier) will be happy to mold specific FST rears with a little less width and a little more height (we actually got a touch of that with the R60A ).

[rickjohnson356]

I appreciate the responses. I forgot to factor in the fact that the rear tires are 22.5 inches vs 20 inches tall for the fronts.

I like the idea of a single spec gearbox to help reduce the entry cost of racing in this class.

My original post is more of a question than a request for a rules change this early in the existence of the class. After all, I am still just building my FST car, and don't even have a dog in the fight (yet).

I am looking forward to running in this class, Completion of the car is dependent on, of course, available funding for the project