S.A.S.C.
Solo => Technical Talk => Topic started by: Reijo on May 17, 2017, 04:01:46 AM
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I have heard a number of questions about wheels and tires recently and so I thought I would include the section in the (SCCA) rules about them here for your information:
13.3 TIRES
Tires may be replaced with any size that fit the allowable wheels and fender wells without modification. Tires may be excluded for, but not limited to, low volume production, extensive availability limitations, and specialty design.
Tires must meet the following requirements to be eligible for use in Street category. No tire model will be eligible for Solo® competition until it meets all requirements of this Section. Tire models not meeting the requirements
by April 30 are not eligible for Solo® competition until after the Solo® National Championships of the year.
A. Specifications
1. Minimum UTQG Treadwear Grade of 200.
2. Minimum molded tread depth of 7/32” as specified by the manufacturer.
3. Listed in a current year or prior 2 years of the “Tire Guide®” and/or the “Tread Design Guide®” (www.tireguides.com).
4. US Department of Transportation (DOT) approval.
5. Tires must be designed for highway use on passenger cars.
B. Eligibility Requirements – The following are prerequisites before a tire can be used in competition at National Solo® events.
1. Tire availability – Tires are considered available when competitors can take possession through retail channels. Pre-orders are not considered available.
2. Tires must be equally available to all competitors. Tires that are in short supply do not specifically violate Section 13.3. Extensive shortages may result in the tire being placed on the exclusion list until supply is replenished.
Tire variations differing from standard specification, delivered only on a limited basis, or only to selected competitors may not be used.
62 — 2017 SCCA® National Solo® Rules
13. Street
3. Tire models must have tires available in at least 4 rim diameters and in at least 6 sizes which meet these requirements.
4. Material Change – Tires which previously met the eligiblity requirements that undergo a significant compound change, tread pattern change, or other significant redesign reset the requirement for eligibility described in Section 13.3.B.
5. A tire model which was previously allowed by these rules continues to be eligible for competition until specifically disallowed.
6. Re-introduction – Models that were once discontinued will be considered a new model once reintroduced and must meet all the requirements of Section 13.3.
C. Other
1. Any tire which is OE on a car eligible for Street Category may be used on that car in Regional Solo® events. OE tires must meet all requirements of Section 13.3 to be eligible for National Solo® events.
2. Tires may be shaved evenly and parallel to the axis of rotation, but may not otherwise be siped, grooved, or modified.
3. No recap and/or retread tires may be used.
4. The tire must not appear on the following list, which may be altered at any time by the SEB upon notification of membership.
• No tire models are currently listed.
13.4 WHEELS
Any type wheel may be used provided it complies with the following:
A. It is the same width as standard and as installed it does not have an offset more than ±7.00 mm (±0.275”) from a standard wheel for the car. The resultant change in track dimensions is allowed.
B. Wheel (rim) diameter may be increased or decreased 1” from the standard part.
Wheel spacers are permitted provided the resultant combination complies with the offset requirements of this Section. On vehicles supplied with an OE wheel spacer, the wheel spacer shall be considered as a part of the wheel.
Wheel studs, lug nuts, valve stems (including pressure-relief types), and/or bolt length may be changed. Wheel bolts may be replaced with studs and nuts but the number of fasteners may not be changed. Tire pressure monitoring
sensors may be removed.
Centerlock/Spline Drive/Knock-off type hubs may be converted to lug type hubs provided the resultant combination complies with the offset requirements
of this Section.
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Thanks for posting and for putting up with all the question we all ask you.
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I know a lot of people find the (necessarily) dense wording of the SCCA rules confusing, so here's a TL;DR summary:
- If you bought your tires at a regular tire store, and they aren't marketed as competition, track, or semi-slick tires, they're almost definitely legal.
- If your tires are marketed as competition, track, or semi-slick tires, then look for a two- or three-digit treadwear rating on the sidewall. If it's 200 or higher, then they're probably legal, but it would be a good idea to check with someone at registration to be sure.
- If you're running the wheels that came on your car from the factory, then they're legal.
- If you're running different wheels than what came from your car from the factory, but a) they're the same width as the factory wheels, b) they're no more than one inch bigger or smaller in diameter than the factory wheels, and c) their offset (including any spacers you're running) is no more than 7 mm greater or less than the factory wheels, and d) they're made of metal, then they're legal.
There are a few edge cases besides the ones described above, but the guidelines above hold for 99% of people.