What's up with the tire width spec? Penalizing lighter cars

[JCraven]

Heavier cars need wider tires. Lighter cars are often faster with narrower tires.

 

NASA and others have done testing with Pro7 RX7 race cars with both 205 and 185 width Toyo RA1s on both the stock 5.5" rims and 7.0" rims. Reports and lap time results show that the 185s are actually quicker than the 205 tires. Wider isn't always better.

 

NASA is moving in the direction that lighter cars have more competion potential than heavier cars. That is definitely true if one attempts to control the tire width. While I hear arguments that heavier cars are harder on tires and brakes/suspension for example, their chassis are usually designed with larger brakes and corresponding components to control that weight.

 

Wind resistance is also a factor. Wind resistance becomes a much larger factor in reaching higher speeds on the long straights as compared to weight/power ratios. If lighter cars have to run a higher weigh/power ratio (more weight or less power), then the heavier cars should be able to reach higher speeds and probably pass the lighter cars at the ends of the long straights at many tracks.

[roadracetransam]

You are right heavy cars do need wider tires. It is a mistake to set a tire spec based on what class you run, because within some classes there is as much as 1500 lb difference in weight between the cars. You can't expect the heavy cars to wear the same size tires as the light cars, or does NASA really think all cars put the same force on the contact patch regardless of weight.

Now for the light cars, they don't have to wear wide tires, they acctually get rewarded (points DEDUCTED) for wearing the tire size optimal for their performance, while the heavy cars get penalized for wearing their factory sizes.

Example: Dodge SRT-4 in TTC base class TTE, stock size 205, normally running 225, increased tire size 20mm for free.

Pontiac WS6 in TTC Base class TTC, stock size 275, running 295's gets +15 points for increasing tire size by the same 20mm!

 

As for myself I got hit with 20 points for tires, while the fellow I came in second to, in the last four races, got hit with 10 for his R-compound. Was I really that big of a threat, to be moved up a class on tires alone?

 

PS: I am not even going to mention weight reduction. Come to think of it tires, weight, mufflers, and shocks/springs is the only thing I changed on the car and I went from base class TTD to TTA. Something is wrong!

[AU N EGL]

Larger cars too. Covettes get penilzed for running stock size tires, 255s

[kbrew8991]

sheesh, even my small, somewhat light car gets hit for its rear 225s

[Jan in Omaha]

The 205mm max works great for me in either of my TTF cars.

[IGZOSTD]

This new tire spec for class is just not right . Our cars should be classed with there OEM tires . The new dot r and upgrade size points is more than enough of a points hit .

[Pat L.]

It is too difficult for regional directors and techs to know what size tire came from the factory on every single make/model including all the OE sport models. I'm a huge fan of the new tire rule because it allows the participants to aid in keeping compliance.

 

My feeling is that if a competitor chooses to run 335's on his/her vette or other big sports car, then they should have to pay accordingly for that much mechanical grip. I think the rule is in line with the gains that can be yielded with the use of big sticky tires.

[Tom A]

My feeling is that if a competitor chooses to run 335's on his/her vette or other big sports car, then they should have to pay accordingly for that much mechanical grip. I think the rule is in line with the gains that can be yielded with the use of big sticky tires.

Isn't "that much mechanical grip" factored in to the base class?

[slink]

i disagree pat. that is what the base classing should be for. why shold a car get hammer on points for its stock tire size. i was told at the nationals that anything could be looked up online. just have the competitor have bring a oe printout? all honda and acura cars have the tire size on the door jam.

[StealthTT]

It is too difficult for regional directors and techs to know what size tire came from the factory on every single make/model including all the OE sport models. I'm a huge fan of the new tire rule because it allows the participants to aid in keeping compliance.

 

My feeling is that if a competitor chooses to run 335's on his/her vette or other big sports car, then they should have to pay accordingly for that much mechanical grip. I think the rule is in line with the gains that can be yielded with the use of big sticky tires.

 

That'd be great if all the cars weighed the same. Unfortunately weight has a huge effect on traction. This isn't about a car running monster tires to get a huge advantage in traction. This is about using a tire width that is adequate for the weight and power of the vehicle.

 

No one expects an official to have every car's specs memorized. OEM tire width could easily be stored in a database for an official to look up if the OEM tire width is in question. It could be listed alongside curb weight in 6.3.2 of the rules. It doesn't even have to be on a computer. It could be printed out and stuffed in a back pocket.

 

I think the intent was correct, but this is another case where one rule meant to simplify inspections causes an unforeseen consequence. This rule doesn't equalize all the cars (big and small) in the class. The penalty for increasing tire width over OEM and/or running race tires is adequate to equalize cars. I think using the OEM width is necessary and easily enforceable.

[daveh]

While I like the rule the only callout that I have is that it would be nice if those who run staggered sizes could take the average width of the two rather than the wider of the two. A car like a 911 would really get penilzed on this one because they have to run a larger tire in the rear. Anyone agree with this??

[kbrew8991]

I'm in the same boat, I have to take 4 points for the pair of 225s I run (205 is the "max" in TTF) even though the fronts are 205s

 

I could switch to 195/205 Hoosier R setup, but if I'm reading right I don't get the 1 point (or whatever it is) back for the fronts beind undersized for TTF and that pushes me one point over to TTE and I'm not going there.

 

it just seems a little unfairly inconsistant, if one end is larger you get slapped, but if one end is smaller you don't get the benifits...

Edited December 11, 2006 by Guest

[GooRoo]

i disagree pat. that is what the base classing should be for. why shold a car get hammer on points for its stock tire size. i was told at the nationals that anything could be looked up online. just have the competitor have bring a oe printout? all honda and acura cars have the tire size on the door jam.

 

 

Couldn't it be that they already figured this out? The base class could already have factored in the OEM size tires and taken points away based on the fact that the car will have to run smaller than normal tires.

 

That way they know to run stock size tires you will have to add X number of points.

 

Completely made up example:

 

Car Xray was base classed in TTC*, which in the new system has a default tire width of 245. However the car has a oem size of 275. That 30mm of extra width will cost 7 points, so they redo the base class so that it's TTC, and the problem is solved.

 

If a person wants to run oem size 275's, they can spend the 7 points and get back to exactly where the car used to be, if not, they can use that 7 points elsewhere.

 

End of the example

 

Now, they may have changed the points/base class on the car for other reasons as well, so the calculation is less direct in most cases. In any case, this will simplify the tire rules *alot* for compliance checking. All you need is base class and you have the point values for the tires.

 

I'm not yet 100% for or against the change, I'm just trying to say that this method could be setup to not affect the classing of the cars at all, while simplifying the tire rules if that was their goal.

[roadracetransam]

i disagree pat. that is what the base classing should be for. why shold a car get hammer on points for its stock tire size. i was told at the nationals that anything could be looked up online. just have the competitor have bring a oe printout? all honda and acura cars have the tire size on the door jam.

 

 

Couldn't it be that they already figured this out? The base class could already have factored in the OEM size tires and taken points away based on the fact that the car will have to run smaller than normal tires.

 

That way they know to run stock size tires you will have to add X number of points.

 

Completely made up example:

 

Car Xray was base classed in TTC*, which in the new system has a default tire width of 245. However the car has a oem size of 275. That 30mm of extra width will cost 7 points, so they redo the base class so that it's TTC, and the problem is solved.

 

If a person wants to run oem size 275's, they can spend the 7 points and get back to exactly where the car used to be, if not, they can use that 7 points elsewhere.

 

End of the example

 

Now, they may have changed the points/base class on the car for other reasons as well, so the calculation is less direct in most cases. In any case, this will simplify the tire rules *alot* for compliance checking. All you need is base class and you have the point values for the tires.

 

I'm not yet 100% for or against the change, I'm just trying to say that this method could be setup to not affect the classing of the cars at all, while simplifying the tire rules if that was their goal.

 

The Problem is the they did not reclassify Car Xray to TTC, but left it in TTC*, just like last year!

 

Doing tire sizes according to Base Class makes as much sence as doing weight according to Base Class.

Lets put all TTC cars at 3300lb, if you weigh less you get points, if you weigh more you get points deducted.

The tire size rule and weigh rules hit heavy cars big time. You can't reduce the weight to make the smaller tires work, and you can't keep the weight because the tires will be in ineducate. So, let's forget about turning fast and brakeing, we will build monster engines and be fast in the straits. That is out too!!! 8.7:1 weight/HP ratio won't get you far. So, it looks like SUR for the big cars, but that costs too much.

[JCraven]

 

Couldn't it be that they already figured this out? The base class could already have factored in the OEM size tires and taken points away based on the fact that the car will have to run smaller than normal tires.

 

That way they know to run stock size tires you will have to add X number of points.

 

I'm wondering if the new TT/PT/ST model is penalizing light cars precisely because some people aren't running the optimum size tire for their heavier cars. Why create some arbitrary tire limit and then adjust everything around that arbitrary limit to fix the fix that was intended to solve a different problem.

 

See, my point is that this is getting very complicated, a complication that is creating a barrier to new competitors by alienating them as we are seeing in this thread.

 

My recommendation is to let people run whatever tire size they want and can afford. Last years TT rules were adequate for tire size purposes.

[StealthTT]

 

I'm wondering if the new TT/PT/ST model is penalizing light cars precisely because some people aren't running the optimum size tire for their heavier cars. Why create some arbitrary tire limit and then adjust everything around that arbitrary limit to fix the fix that was intended to solve a different problem..

 

The new tire rules penalize heavier cars. They give free tire points to the lighter cars.

 

See, my point is that this is getting very complicated, a complication that is creating a barrier to new competitors by alienating them as we are seeing in this thread. .

 

It's not that complicated. If anything it oversimplifies and misses the point of what actually happens in the real world. In the real world not all the cars weigh the same, even if they have the same weight to power ratio. Heavier cars need more tire in order to corner and brake as quickly as a lighter car. It's very simple grassroots physics.

 

My recommendation is to let people run whatever tire size they want and can afford. Last years TT rules were adequate for tire size purposes.

 

Sure, then to be competitive we'll have to run $2500/set custom CCR wheels and $1400/set in Hoosiers. The purpose of most of the rules is to keep this racing thing in some sort of budget and match up some what equal cars.

 

If they don't want to base class the car by the OEM tire size, then a sliding scale for tire width based on weight is the most fair.

 

For example a TTC car weighing 2700lbs would have a base size of 245. While another TTC car weighing 3600lbs would have a base size of 335. In this example every 100lbs will let you run 10mm more. This takes into account all of the physics involved in a tire's traction.

 

Although it's slightly more complicated it would still be easily understood and enforced. If an official can't read and apply a sliding scale, then I'd question his abilities to perform his job.

[JCraven]

 

 

The new tire rules penalize heavier cars. They give free tire points to the lighter cars.

.

 

Not necessarily, depends on the base class of the light car. Greg has already stated that the new classing model penalizes the light cars so if a light car is in TTF and normally runs a 205, they they do not get free points. Other light cars are getting penalized too, like the MR2 example somebody used.

 

 

It's not that complicated. If anything it oversimplifies and misses the point of what actually happens in the real world. In the real world not all the cars weigh the same, even if they have the same weight to power ratio. Heavier cars need more tire in order to corner and brake as quickly as a lighter car. It's very simple grassroots physics.

 

Yes, we agree but what gets complicated is the arbitrary tire limit that will affect different cars in different ways. The classing model will have to take into account what size is optimum for a car and class accordingly. If it doesn't , well then it is simple and the heavy cars are penalized more.

 

My recommendation is to let people run whatever tire size they want and can afford. Last years TT rules were adequate for tire size purposes.

 

Sure, then to be competitive we'll have to run $2500/set custom CCR wheels and $1400/set in Hoosiers. The purpose of most of the rules is to keep this racing thing in some sort of budget and match up some what equal cars.

 

If they don't want to base class the car by the OEM tire size, then a sliding scale for tire width based on weight is the most fair.

.

 

Have you thought about how much it can cost to test out all of the variables to get the most performance for the least amount of points.

 

Cams +6 - how many cams will one want to test?

Compression - sliding - will affect which is the optimum cam

Displacement - sliding - will affect compression and optimum head mods and cams.

Transmission - straight cut gear transmissions are only +3. Last I checked, these cost about $15K although one can get lucky and find one used for around $400.

 

 

The list goes on and on.

[roadracetransam]

Sure' date=' then to be competitive we'll have to run $2500/set custom CCR wheels and $1400/set in Hoosiers. The purpose of most of the rules is to keep this racing thing in some sort of budget and match up some what equal cars.

 

If they don't want to base class the car by the OEM tire size, then a sliding scale for tire width based on weight is the most fair.

.[/quote]

 

Have you thought about how much it can cost to test out all of the variables to get the most performance for the least amount of points.

 

Cams +6 - how many cams will one want to test?

Compression - sliding - will affect which is the optimum cam

Displacement - sliding - will affect compression and optimum head mods and cams.

Transmission - straight cut gear transmissions are only +3. Last I checked, these cost about $15K although one can get lucky and find one used for around $400.

 

 

The list goes on and on.

 

I don't get your reply here.

But, for the most part, most racers do not have to do much testing, since most of us drive cars with powerplants that have been around for quite a while. So you have a pretty good idea what benefit, how big benefit, and drawback each part will give you. If you really don't know, than you must not be doing your homework before reaching for your wallet.

[StealthTT]

Not necessarily, depends on the base class of the light car. Greg has already stated that the new classing model penalizes the light cars so if a light car is in TTF and normally runs a 205, they they do not get free points. Other light cars are getting penalized too, like the MR2 example somebody used.

 

 

There's some light cars that benefit and some heavy cars that benefit. I looked at a dozen or so cars that are commonly raced. It was predominantly the heavy cars that were penalized.

 

Yes, we agree but what gets complicated is the arbitrary tire limit that will affect different cars in different ways. The classing model will have to take into account what size is optimum for a car and class accordingly. If it doesn't , well then it is simple and the heavy cars are penalized more.

 

If it must be simple for the official, then the base class would be the best place to assess penalties for tires. A blanket rule doesn't work for every car. The cars with bigger or smaller OEM tires were not re-classed to reflect the change between the 2006 and 2007 rules. When looking at the common cars raced the heavier cars with larger OEM tires were penalized by this rule since they were not re-classed.

 

Have you thought about how much it can cost to test out all of the variables to get the most performance for the least amount of points.

 

Cams +6 - how many cams will one want to test?

Compression - sliding - will affect which is the optimum cam

Displacement - sliding - will affect compression and optimum head mods and cams.

Transmission - straight cut gear transmissions are only +3. Last I checked, these cost about $15K although one can get lucky and find one used for around $400.

 

I'm not sure of your point. Most people let the company selling the parts prove the gains if an independant test has not been done. I routinely see comparisons in magazines with dyno numbers and sometimes laptimes.

 

But anway, there's a big difference between tires and transmissions and that's reflected in points. Regardless of cost, how many seconds will a straight cut tranny save on your lap time? Now how about a change from 245's to 275's? RA1's to Hoosiers? I think the points assessed for those are adequate.

 

I think the rules committee just forgot to factor in the considerable differences in weight when making the class base tire width rule. The physics of traction is quite simple and weight is a very important factor in that equation. On paper it probably looked good to simplify this. In the real world, it should either be dealt with in the base classing or using a sliding scale.

[Shawn M.]

The new tire rules penalize heavier cars. They give free tire points to the lighter cars..

 

 

You couldnt be more wrong. The new tire rule penalize all cars. Light, heavy, they all get a ding for tires. Big ding for compound, more ding for width. Its a big ding.

 

And I understand that many cars were already adjusted for the ding that some speculate should be done. So even tho some cars didnt move in base class, that was their adjustment. Enjoy!

[860TTC]

The new tire rule penalize all cars.

Enjoy!

How can you make that comment with a straight face? Sounds like the new rules work for you and you could care less about the other competitors.

 

Light cars come with narrower tires – heavy cars come with wider tires. So, now many heavy cars are penalized for running stock sized tires? These are the tires sizes that were used to get performance data on the car to begin with. Now we are in uncharted territory on the new performance of the car with zero point tires.

 

What about keeping the stock tire sizes as base? You can go to the tire rack.com to find that at any time!

[Markus]

How can you make that comment with a straight face? Sounds like the new rules work for you and you could care less about the other competitors.

 

Well...first of all, Shawn doesn't say much of anything with a straight face....

 

But in this case, he was being truthful. Shawn's weapon of choice is an old-arse VW that is very light. I think he's limited to small rims so he combats this by going really wide on the rubber. If he wants to run really wide 13" tires in TTE, he will also pay the penalty...just like the heavier guys will in their respective classes...

 

Also, go back and look at Kbrew's example. His MR2 is a lightweight TTF car, and he will pay a penalty for the rear 225's. So - the tire rule is probably having an impact, on every weight of car, at every level.

 

- Mark

[kbrew8991]

I think the tire rule stuff is a little silly, but I can deal with it. its another way to equal out cars a little, and I'm sure they put ample research into how it would affect people's combinations, times, performance etc.

 

Guys who run staggered sizes really get screwed over tho, they aren't being treated fairly! Thats the change I'd like to see. I'll take the appropriate points if staggered sizes are treated consitantly (charged the same way if they're above or below thier stipulated tire size)

[Shawn M.]

The new tire rule penalize all cars.

Enjoy!

How can you make that comment with a straight face? Sounds like the new rules work for you and you could care less about the other competitors.

 

 

With a straight and serious face, I can tell you that the new rules screw me more than the average bear. I dont now, nor have I ever used a 185mm bicycle tire on my car. (This is not a formula vee!) So in addition to the being too light penalty for the base class, I also pay a too wide a tire penalty plus the its so not worth it penalty to try and make 20HP more than stock from a little 8v motor only AFTER ive already spent the money and now points on building it. So again, your wrong, the rules do not work for me.

 

And you would be wrong again in assuming I do not care about my competitors. I hope they get screwed by the rules at least as much as I did. From what ive read on the rules so far, most, not all, got affected with these new rules.

 

Adapt and overcome or stay home. I see that as out options here.

Edited December 12, 2006 by Guest

[kbrew8991]

whats really funny is that my overall points didn't change

 

19 on the old system, TTF

19 on the new system, TTF

 

The new system almost allows enough room to tweak a couple things to close the 1.7 sec gap I had behind 1st and 2nd place too.... but now its just going to be aiming to hit minimum weight. ah well.

 

the older system really seemed to favor low class cars with lots of parts versus working with a stock car + tires and maybe 1 mod. maybe the newer system will get some better parity between those 2 styles of car...

Edited December 12, 2006 by Guest