twistedwankel wrote:400 or greater utqg All Season only for now.
Later from a list we provide to cover all sizes needed.
Kumho AST (grandfathered since I own them
), Yokohama, Goodyear/Sumitomo, Hankook, Bridgestone/Firestone, BFG?
Over 3000LB car = 225mm max width tires
2800-3000Lb car = 205mm max width
2600-2800LB car = 195mm max width
Under 2600LB car = 185mm max width
Does that cover everyone? Does that kill the horsepower well enough? We can still get them shaved when new right? 3/32" min tread depth to run this class to allow for wear. That should be just above the wearbars. I really don't see anyone being able to run 11/32" stock treads without chunking and squirming like mad.
Got to start somewhere and weight is great. Don't think you can allow after market rims unless they are same as stock width and plus or minus 1/4" offset like in SCCA.
I like some of this and some of it I don't. I do like the weight limit thing, but I'd never suggest it because I have a lightweight car and wouldn't want to be accused of building an "I class".
Of course, anything to do with weights brings up "how do we determine the weight of the car" and "is it with or without fluids", "with or without options", "with or without driver", etc. Since we don't have scales handy, it's a bit of a can of worms... especially for any car that's right on the threshold using whatever reference we use. For instance, say the published weight is 3020, but they've removed their AC system, which weighs 70 pounds. Do we make them run tires for their "actual" weight of 2950? Or on the flip side... the published weight is 2991, and they've added 20 pounds of stereo equipment, or they're just a heavy driver... do we allow them to run in the over 3000 bracket? I'm not trying to be difficult, but these ARE the questions that will inevitably come up. A good rule set must be ready for it.
I think your scale could stand to go lower (and maybe even higher... lots of heavy cars on the road these days). There are a lot of sub-2400 pound cars (Miata, MR2, Yaris, older Hondas, various other economy & small sports cars), and if you go back to the 90's and earlier, there are plenty of sub-2000 pound cars.
I don't think I'd force anyone to run on 155's (though I did have them on my Spitfire...), and 165's are odd ducks, not much selection. But, you could go with something like 175 for sub-2000.
The part I don't like is worrying about tread depth and wheel width. That doesn't quite fit with the FAST "Keep it Simple" philosophy. Let the treadwidth and whatever other tire parameters we come up with be THE limitation. Think a 195 tire is going to work well on a 9" rim with +25 offset? More power to you. Want to mod your suspension to maybe help you get more out of your minimalist tires? Have at it. Tread depth? Meh. Like any other tire, as long as it's not corded, it's good. K.I.S.S.
With that in mind, rather than a weight-size list... maybe we could do it with a formula? A couple minutes in Excel, and I think I have something that might work... Round the weight up to the next 100. Divide by wheel diameter, add 2x wheel diameter, and go up as needed to reach a standard tire width. Minimum width 175, max with 235, minimum aspect ratio 50.
It would impose a slight width penalty for choosing larger diameter wheels with lower profile tires. And the aspect ratio limit would prevent running really low profile wide tires on small wheels for a heavy car.
Rounding weight up to the next hundred makes finding an exact weight less critical. We could even estimate actual weight (look up weight and add/remove from it based on items added/removed from the car). With the formula, as long as we're close, I think the result is acceptable. We could even go as far as to allow a driver over 200 pounds to add any weight over 200 to their vehicle weight for the calculation.
This could work.
Some examples attached.
