IRRA tire rules

[stevphens]

My IRRA Retro CanAm needs .550 wide tires, while my Flexi needs .800 wide tires. Can I legally trim the tires down to .750 diameter part way across, leaving .550 width at the Retro legal .815 diameter so they can later be trimmed down all the way across and used on the Flexi when the .550 width is too small diameter for the Retro? That is, can the .750 diameter be considered sidewall during Retro tech (since there is no way the .750 diameter can touch the track) and therefore not be measured for minimum tire diameter?

[brassrodman]

Why would you run .550 wide tires on retro?

[Bill Fulmer]

My IRRA Retro CanAm needs .550 wide tires, while my Flexi needs .800 wide tires. Can I legally trim the tires down to .750 diameter part way across, leaving .550 width at the Retro legal .815 diameter so they can later be trimmed down all the way across and used on the Flexi when the .550 width is too small diameter for the Retro? That is, can the .750 diameter be considered sidewall during Retro tech (since there is no way the .750 diameter can touch the track) and therefore not be measured for minimum tire diameter?

My guess and this is only a guess is no. If you start the race with 10mm of the tire the correct size you could wear that down in one lane and be undersized for the rest of the race.All the techs I have been through take the measure of the full width of the tire.You can run a narrower tire but the rubber has to be removed to the rim.PM Noose and ask him,he is the head tech guy with the IRRA. Bill

[stevphens]

Why would you run .550 wide tires on retro?

The car is too tight with wider tires. I tried removing weight and adding weight in different locations without success, changed wheelbase and guide lead, tried 3 different bodies, different compound tires then finally narrowed the rear tires until the handling was close to neutral. I welcome other suggestions to solve the tight problem...

[Noose]

Sorry the answer is no. This has been raised and an answer given:

3-24-09Q: Does the entire diameter of a rear tire have to meet the stated specification?

A. Yes. The tire diameter must meet or exceed the minimum specification across the entire width of the tire.

You may find this in the Q&A section on the the IRRA Website.

IRRA Website - Q&A Section (http://irraslotracing.com/id37.html)

Tires may be narrowed but the min diameter must always be met.

[RapidRick]

Rick: I have not gone crazy trying differant tire choices, but I have driven 5 unique chassis on my two tracks. Every time I come back to Kelly Blue or Purple Label Tires.

If you want more grip try Orange..the Intimidator label has bite that I don't like but it is fast on our Grandstand.

[dominator]

Rick will you have these available for 3/14?

[z-ya]

If you stiffen the car up it should make it looser , try a larger main rail or add a secondary rail .