Comparing car lap times: Equal tires?

[rice_classic]

Originally Posted by fatoni

i dont know why you keep bringing me up. i didnt even vote. this whole poll misses the only point i was trying to make. i could just as easily make an example out of the v6 mustang and its 114mph speed governor as an example of manipulating the ecu for an accurate comparison.

It's been fun having a devils advocate with such tenacity.

The part in bold actually proves the premise regarding the tires. The point is "What are you testing." Are we at the Bonneville Salt Flats? If so, then yes, if one the of the cars has a speed governor and the other doesn't should we remove the governor? UH DUH! of course we should otherwise there's NO POINT IN DOING THE COMPARISON. (sorry for yelling).

So here I am at dinner the other night with 10 other S2000 and former S2000 owners (old group that gets together once a week) and we're talking about lap times at a new track in town. They wanted to know what my best lap time is at the track in my FRS since I'm an instructor there. I told them my best is a 2:10. They recently did a track day as a group and only 2 guys has stock cars (except tires) and the fastest of the two was on Dunlop Star Specs but the rest of the car unchanged and I think he did a 2:06. Is the FRS 4 second slower at that race track than the S2000? No. Is the S2000 4 seconds faster? No. All we can definitively determine is that

- The FRS is 4 seconds slower with HP Primacy tires than an S2000 with Dunlop Star Specs. We learned that there's a difference in lap with those two variables and those 2 drivers.If we put both cars on Dunlop Star Spec's (which I want) and did laps with the same driver in each car and then the FRS did a 2:08 to the S2k's 2:06 then and only then could we definitively say the S2k is 2 seconds faster than the FRS.

And the comparison holds water because like stated above, we can't compare the cars with OEM tires because the OEM tire for the S2000 is not produced anymore. So then what? (rhetorical).


As it stands now a vote of 33 to 5 for similar tires is essentially proof enough.

[fatoni]

Originally Posted by Kunzite

fatoni, that was a joke; obviously you can vote at most once.
Please don't forget about my "what is stock" question: is it the Michelin Primacy HP equipped GT 86, or the Bridgestone Turanza equipped one?

Manufacturers would do lots of things to hide deficiencies, IMO. Tires, "sport" suspensions, electronic stability controls... this way they can put apparently impressive numbers with a completely unremarkable chassis. Of course, it won't always result in stickier tires being used, and it's not always about performance.

The post before me was talking about the undersized brakes of a stock (incl. tires) NISMO 370z, from what I understand. And it was a good thing that such issue was discovered.

TheRipler, still it would be better than comparing Turanzas with Yoko A048s, or something.

you arent funny

however the car they test comes is stock. look at each review and see what they used.

its strange that in an attempt to isolate tires from other things that change the car you actually lump them together with electronics and suspension. you act like when a manufacturer uses good tires its sandbagging but when you want to use good tires its fair.

what is it that you think the chassis is responsible for? what makes one chassis inferior to the next? saying companies use suspension, tires and electronics to hide deficiencies has me confused as to what youre thinking

[fatoni]

Originally Posted by rice_classic

It's been fun having a devils advocate with such tenacity.

The part in bold actually proves the premise regarding the tires. The point is "What are you testing." Are we at the Bonneville Salt Flats? If so, then yes, if one the of the cars has a speed governor and the other doesn't should we remove the governor? UH DUH! of course we should otherwise there's NO POINT IN DOING THE COMPARISON. (sorry for yelling).

So here I am at dinner the other night with 10 other S2000 and former S2000 owners (old group that gets together once a week) and we're talking about lap times at a new track in town. They wanted to know what my best lap time is at the track in my FRS since I'm an instructor there. I told them my best is a 2:10. They recently did a track day as a group and only 2 guys has stock cars (except tires) and the fastest of the two was on Dunlop Star Specs but the rest of the car unchanged and I think he did a 2:06. Is the FRS 4 second slower at that race track than the S2000? No. Is the S2000 4 seconds faster? No. All we can definitively determine is that

- The FRS is 4 seconds slower with HP Primacy tires than an S2000 with Dunlop Star Specs. We learned that there's a difference in lap with those two variables and those 2 drivers.

If we put both cars on Dunlop Star Spec's (which I want) and did laps with the same driver in each car and then the FRS did a 2:08 to the S2k's 2:06 then and only then could we definitively say the S2k is 2 seconds faster than the FRS.

And the comparison holds water because like stated above, we can't compare the cars with OEM tires because the OEM tire for the S2000 is not produced anymore. So then what? (rhetorical).


As it stands now a vote of 33 to 5 for similar tires is essentially proof enough.

it sounds like you never understood my point at all. im not saying switching tires isnt a useful tool. im saying that its one of many useful tools. you dont need to be on the salt flats to run into that limiter. if i can approach 114 in an ae86 at sow and surpass it in a stock itr, the 300 hp mustang will be on that governor a lot. i never said the comparison doesnt make sense. it just makes as much sense as a lot of other comparisons. tires will change lap times, so will that governor. i agree that tires and drivers are variables. what i have an issue with is that you make an argument like brake pads, shocks, weight etc. arent variables. i dont know how to respond to that.

a poll is never proof of facts or reason. its a proof of opinion and nothing more. even if it was, this is an frs forum. the data was bound to be biased from the start.

again, this poll was never about the issues that i had with peoples reasoning. the problem i had was that people are using a specific argument and only accepting a part of the conclusion that the argument leads them to.

[Kunzite]

fatoni, so if I'd buy a Bridgestone Turanza equipped GT 86 and I want to switch to Michelin Primacy HP, and compare my car with others (let's say a Mustang with PZeros, or a high grip tires in any case) - I shouldn't do that because my car won't be "stock", and it wouldn't be fair; I should keep the all seasons instead.
OTOH, another person who bought an identical GT 86 but with Michelin Primacy HPs can do it, because his car is "stock".
So the exact same car is both stock and modified. Thank you.

I don't have to artificially single out the tires; as I've already said several times, they're singling out themselves since, you're supposed to change them - and quite often, with different types (it can even be required by law). Do that with e.g. suspensions and bye-bye warranty, or worse. In the same time, there's no guarantee that:
- when testing, the exact same model of tire as provided when the car was bought is still available
- the dealer would keep delivering the car with the same tires, during its entire lifetime

An example of hiding deficiencies is the first A Class. Its rollover issue was "fixed" not by a new chassis, but with wider tires, modified suspensions and ESP. Even if the end result was meeting standards, I would still call that chassis "inferior", from a stability point of view.
But it can be e.g. a hot hatch, as well - take a "pedestrian" chassis and "make" it into a sports car, instead of designing a dedicated one. Or a Mustang which puts down excellent skidpad results, due to it's PZero tires.

Sandbagging? As in hiding one's strength?

By the way, we are understanding your point perfectly; we just disagree with it (but not with the idea of comparing cars with the dealer provided tires, if that's what you want to measure). It's you who doesn't even care about the points we're making.
And by the way, when you want something specific you'd normally use the single proper tool for the job, not all the tools you have, at once - or none at all, fighting the issue barehanded

[fatoni]

Originally Posted by Kunzite

fatoni, so if I'd buy a Bridgestone Turanza equipped GT 86 and I want to switch to Michelin Primacy HP, and compare my car with others (let's say a Mustang with PZeros, or a high grip tires in any case) - I shouldn't do that because my car won't be "stock", and it wouldn't be fair; I should keep the all seasons instead.
OTOH, another person who bought an identical GT 86 but with Michelin Primacy HPs can do it, because his car is "stock".
So the exact same car is both stock and modified. Thank you.

I don't have to artificially single out the tires; as I've already said several times, they're singling out themselves since, you're supposed to change them - and quite often, with different types (it can even be required by law). Do that with e.g. suspensions and bye-bye warranty, or worse. In the same time, there's no guarantee that:
- when testing, the exact same model of tire as provided when the car was bought is still available
- the dealer would keep delivering the car with the same tires, during its entire lifetime

An example of hiding deficiencies is the first A Class. Its rollover issue was "fixed" not by a new chassis, but with wider tires, modified suspensions and ESP. Even if the end result was meeting standards, I would still call that chassis "inferior", from a stability point of view.
But it can be e.g. a hot hatch, as well - take a "pedestrian" chassis and "make" it into a sports car, instead of designing a dedicated one. Or a Mustang which puts down excellent skidpad results, due to it's PZero tires.

Sandbagging? As in hiding one's strength?

By the way, we are understanding your point perfectly; we just disagree with it (but not with the idea of comparing cars with the dealer provided tires, if that's what you want to measure). It's you who doesn't even care about the points we're making.
And by the way, when you want something specific you'd normally use the single proper tool for the job, not all the tools you have, at once - or none at all, fighting the issue barehanded

would you mind explaining my point to me then, because what you are saying doesnt provide any evidence you know where im coming from.

what about a "pedestrian" chassis is inferior to a "sport" chassis? i still dont get your point on that topic. as far as i can tell for performance, a chassis is to provide stiffness to allow the suspension and other components to do their job. in every type of vehicle stiffness is a good thing so they all have the same goal

[Kunzite]

If you don't understand your own point and must have others explain it to you, then you have a problem :p

So a very stiff bus chassis would be more than adequate for a sports car? I don't think so...

[fatoni]

Originally Posted by Kunzite

If you don't understand your own point and must have others explain it to you, then you have a problem :p

So a very stiff bus chassis would be more than adequate for a sports car? I don't think so...

my problem is that your arguments are childish and incoherent. there have been a number of players in this talk and what usually happens is that we end up with different opinions and bow out. you, on the other hand, keep bringing me back up. instead of discussing my points you talk about me.

no a bus isnt a good sports car for many reasons but things like the original fairlady, integra, coopers (old and new), cobalt, nissans multicar platforms, evo, wrx, civic, etc have all been adequate sports cars. despite coming from pedestrian backgrounds.

[Kunzite]

But you can't let it go either, can you? Remember who started it, on the vs 370Z thread...
And even now, you were talking to me as if I would be unable to understand your point and just pretended I did. Surprised about the response?

My arguments might not be expressed very well but are quite consistent, IMO. They can be grouped into two main lines:
A. tires are not a constant, and they're meant to be changed (no OEM code, same cars can be delivered with different tires etc)
B. why same tires comparisons are valid (depending, of course, in what we want to measure).

And yes, those cars you're mentioning are/were quite good sports cars, because a manufacturer can hide / work around such deficiencies (completely consistent with what I've said). Provided we're not talking about a bus chassis
It also depends on what kind of car you're building, of course. You can't get a Golf (random example) and make an Elise out of it.
But you know such things very well.

[WolfpackS2k]

A few clarifications about the 370Z:

-the brake rotors are not undersized, nor have they ever been. They're 14" people, that's more than large enough for a vehicle of that size/power!
-The upgraded Nismo brake pads and fluid did not solve the brake problem. It merely delayed it's onset.
-The brake problem the 370Z suffers from is a lack of air flow over the brakes.


As to this poll, I voted no. If you think all an automaker does it randomly slap on some tires as OEM and then sells the car that way then you are incredibly naive. When a new car is going through R&D the automaker includes tire selection while developing the vehicle's suspension. If there is a sport suspension with a more aggressive tire utilized you better believe they test those tires as well.

And that is why when you comparison test one car against another (or 2 or 3) in a magazine you use the tires THE VEHICLE WAS DESIGNED FOR.

Of course it is always worth noting what tires are on the vehicles being tested and often times the car magazines point out whether or not a tire is holding back a vehicle's performance. It is not to say that you cannot improve a vehicle's performance by putting on more aggressive rubber. However that is an AFTERMARKET modification and car magazines aren't often in the business of comparing stock vehicles against modified ones.

Kunzite, if an auto manufacturer offers more than one OEM tire for the BRZ/FRS (Bridgestones and Michelins) then the car is stock equipped with EITHER OF THEM. How hard is it to understand that one vehicle can have more than one tire choice stock? That's a decision made by the manufacturer.

[WolfpackS2k]

Originally Posted by rice_classic

And the comparison holds water because like stated above, we can't compare the cars with OEM tires because the OEM tire for the S2000 is not produced anymore. So then what? (rhetorical).

2004+ S2000s (essentially the AP2) came from the factory on Bridgestone RE050s. And yes that tire is still produced.

[midenginebias]

manufacturers dont put good tires on cars to hide things

Disagree with that. A great set a tires can hide so many handling deficiencies.

Certain cars are actually tuned to work with specific tires.

[fatoni]

Originally Posted by midenginebias

Disagree with that. A great set a tires can hide so many handling deficiencies.

Certain cars are actually tuned to work with specific tires.

like what kind of deficiencies?

[Kunzite]

Originally Posted by WolfpackS2k

A few clarifications about the 370Z:

-the brake rotors are not undersized, nor have they ever been. They're 14" people, that's more than large enough for a vehicle of that size/power!
-The upgraded Nismo brake pads and fluid did not solve the brake problem. It merely delayed it's onset.
-The brake problem the 370Z suffers from is a lack of air flow over the brakes.


As to this poll, I voted no. If you think all an automaker does it randomly slap on some tires as OEM and then sells the car that way then you are incredibly naive. When a new car is going through R&D the automaker includes tire selection while developing the vehicle's suspension. If there is a sport suspension with a more aggressive tire utilized you better believe they test those tires as well.

And that is why when you comparison test one car against another (or 2 or 3) in a magazine you use the tires THE VEHICLE WAS DESIGNED FOR.

Of course it is always worth noting what tires are on the vehicles being tested and often times the car magazines point out whether or not a tire is holding back a vehicle's performance. It is not to say that you cannot improve a vehicle's performance by putting on more aggressive rubber. However that is an AFTERMARKET modification and car magazines aren't often in the business of comparing stock vehicles against modified ones.

Kunzite, if an auto manufacturer offers more than one OEM tire for the BRZ/FRS (Bridgestones and Michelins) then the car is stock equipped with EITHER OF THEM. How hard is it to understand that one vehicle can have more than one tire choice stock? That's a decision made by the manufacturer.

About NIZMO 370Z brakes issue: you're right, thanks.

I definitely don't think a manufacturer would randomly change the tires. But do we know the criteria for their choice? I think the Michelins were a deliberate, well tested choice (made by Toyota&Subaru themselves); but why exactly were they chosen? Because the car won't drift with high grip tires? Because other components (e.g. brake pads, fluid, lines) would have to be changed as well? Because of EPA, threadwear etc? Because they have a good relationship with Michelin and are already using such tires in other products?
The Bridgestones could be just some all season tires which were suitable. We know very well the car is untouched...

The tires the car was designed for... which are those, for the GT 86? The Bridgestones or the Michelins? :p
Sorry for pulling your leg; but the thing is, we don't actually know which tires would be those. Maybe (very likely IMO) the car was designed to cope with much better tires; but in the end was shipped with the Michelins for various reasons.
Anyway, I hope my whole "Michelin or Bridgestone" tirade is able to prove a point: that even if comparing "stock" cars, it's important to know which tires were used; because tires are not a constant.
From this to "but how fast it would go, with the same high grip tires as the others" is only a step.

I can see a magazine (and its readers!) being curious about how the GT 86 would compare, with the same tires. Obviously, the dealer's tires should remain as a baseline.

Of course both are stock But IMHO the "modified" car (Bridgestones replaced with the Michelins) is better suited for a "stock" comparison, than with it's Bridgestone tires.

[WolfpackS2k]

I couldn't agree more. If the BRZ was offered with Dunlop Direzza Z1 Star Specs you better believe that is how I would order mine!

BTW if you want a good comparison of the BRZ on stock versus aftermarket rubber check out the article on that in this month's Road & Track:

http://www.roadandtrack.com/special-...transformation

It's pretty sweet stuff. The FR-S goes from being slower around a track than the WRX and MS3 by well over a second to beating them both handily!