Can anyone recommend some light semi-slick ?

J90RDN

Paid Member
I have 9 R888R's sat in the garage that I would weigh, trouble is they are all half worn so would weigh less :tonguewink:
 

NickD

Gold Member
Not sure where you would expect to go with this and what you would expect to achieve by knowing weights. They are all going to be about 11Kg and they will all lose around 0.75Kg for each mm of tread wear.
 
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Not sure where you would expect to go with this and what you would expect to achieve by knowing weights. They are all going to be about 11Kg and they will all lose around 0.75Kg for each mm of tread wear.
Everyone compares weights on alloys. Differences of 1kg seem to be a buying move many times, but nobody seems to care about the weight of the tire, which is on the outer edge of the wheel so its weight takes on more importance than it seems.

Here and here we can check that the differences are not small (yokohama AR1 are 2 KG heavier than nitto NT01 )

In my past racing days, combining a light rim with a light tire gave a considerable advantage (often difficult to explain to the stewards).
I remember that some Michelin S9B slicks in 195 / 50R15 weighed less than 6Kg, In that same size, Ferderals 595RS-R weigh 9.6Kg
 

suj

Paid Member
Yeah in racing every gram can matter, I think what Nick means is for trackdays does it really matter? I have friends who have done what you are saying and now in hindsight for a track car they said it was wasted and on their current track cars they've not bothered and actually did stuff like me by keeping some carpet in for creature comforts.

Also for reference NickD races, does trackdays and owns MOT Motorsport who provide MRF tyres to many customers and race teams.

In theory you can do a lot of stuff, I guess it comes down to cost vs reward, if each tyre is 1kg heavier but give more outright grip, but cost less, which one do you pick?

Also your example of Nitto vs AR1 is flawed, two different sizes (215 vs 205)
 
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NickD

Gold Member
Long post alert!

I have been involved in many many tyre tests. Weight has never, ever been a consideration over the attributes of the tyre and how it delivers driver feel, lap time and consistency.

With the examples above, what is the comparison apart from weight? When you consider that the bead size of a tyre is controlled and so standard across tyres as is the outer diameter and to a reasonable extent so is the width. With rubber being the same density, what is causing the additional weight? Carcase construction and rubber thickness in the sidewall. So the trade off is in the attributes of the tyre. Is a Nitto as good as an AR1 and vice versa?
Is a Michelin slick a better race tyre than a road going RS-R and would you put the lack of weight as the main reason it is?
Would you pick a half worn T1R tyre weighing 7Kg over a new 11Kg R888 for going round the Nordschleife because it weighed less?
Has anyone actually compared their lap times on the same day on the same tyres but with 1Kg lighter wheels and seen a difference in times?
As someone who used to supply light weight wheels, and by that I mean 1 to 2Kg lighter and given them to people, who you will see on TV when you watch BTCC, to test. Not one of them ever said I saved 3 tenths. When asked how it was, the usual comment was "it's a wheel."
Yes you will notice the feel of the car in road driving on bumps and how it "feels" if you drop from a 10Kg wheel to a 7. You will notice it less if you go from 7 to 6. And if you can make that change make a difference to lap time you have likely just produced a better driven lap rather than been limited by the weight. The other thing to think is that the main rotating mass effect is naturally at the outer diameter of the tyre. When they all start with the same rubber they pretty much have the same rotational mass at that point.

Anyway, here are just a few excerpts from test reports.

Tyre lost the sharpness of the initial runs of the day and could be felt to be rolling. Front end still better than the Hankook but back washing out and unable to get power down on release and exit of the corner.

Pictures 2 onwards show the tyre after Race Simulation 2.

Comments against the Hankook.

The Hankook tyre does not have the sharpness of the Achilles and shrieks a lot under cornering, however it does not seem to impinge on lap times. Believes the tyre slides more but does not lose speed in doing so where as the Achilles can bog down. The Hankook was very consistent. The slow time on lap 4 on the Achilles and lap 3 on the Hankook were down to snatching a brake. The Achilles was much harder to be consistent on.

-----------------------------------------------------

Due to the car having standard, and possibly tired suspension, it was difficult to fully isolate issues with suspension and tyres as the car lacked poise and needed to be tipped into a corner and wait for a car to “take a set” which made it hard to comment on characteristics such as initial turn in and stability. The car suffered a lot of understeer in steady state, most likely due to the car but again, this could not be isolated from the tyre.

Oversteer could be induced in the car, particularly at corners like Coppice where the car could then be balanced nicely on the throttle.

All drivers reported that the tyre seemed to rapidly “go off.” That the tyre provided reasonable drive, (within the limitations of the car) but that at a maximum of two laps they became greasy.

My own experience was that they lacked precision and the tread shuffled a lot without offering any real grip as you would expect from what is a sport or “R” type tyre. There was no sharpness to turn in and feel was more through the seat and visual rather than through the steering or brakes.

-----------------------------------------------------

Option Tyre. 20-minute run
Initial feel was the same as the control tyre and as before initially two tenths faster than the control
tyre. However, after 5 minutes the lap times degraded and over the course of the run the tyre lost
time with the resulting end times being two tenths slower that the control tyre, so loosing half a
second or more over the race distance, with the notable point being this began quite soon in the
run.
The driver’s comments were than in the medium speed corners (there is not a particular sustained
high speed corner on the circuit) with high lateral load, the rear of the car was the limiting factor as
the tyre was giving up the lateral grip allowing the rear to drift and limiting power application. The
front gave good turn in and held well.
Wear rates however were significantly greater and in particular the inner, load bearing edge of the
shallow, narrow first groove had worn noticeably.

----------------------------------------------------


And this part is the most telling.

This first tyre weighs 8KG

The car was initially run in the morning. There were several red flags that limited time. There was the usual set up laps prior to getting any meaningful data. Comments were that the main and faster driver “---”. These were that speed was limited by understeer on power. In particular:

Hamilton a fast left hand kink required a big lift and car felt unstable.

Williams a slower right hand 100 degree corner which exits on to the back straight. This is the longest straight on UK circuits and so exit speed is crucial. Understeer was preventing early power application.

Coram A fast, near 180 degree long bend which tightens in the last part before a tight left exit corner. The car felt unsettled and lacked ultimate stability.

The fastest lap was 2:18.5. I do not feel this is a particularly fast time given the power of the car.

..........................


This tyre is wider, but weighs 10Kg

A red flag after 3 laps allowed the pressures to be checked. Front left had risen to 36 and rear to 32 on rear. After a long delay allowing the tyres to cool, cold pressures were set to 22 front and 24 rear. A further 35 minutes of running resulted in 32.7 front and 30 rear.

Total run time 50 minutes

Driver comments


On the initial short flagged run, the driver felt the tyre took a lap and a half to switch on. That once they did they were balanced with vastly reduced understeer and that they were “stable and inviting”.

The second driver also reported better balance but that still did have some push onto Bentley Straight.


Fastest Lap 2:14.5

..........................

This tyre is the same as the second tyre, just a different compound. So weighs 10Kg

Replacement compound.
Similar runs were performed with the replacement tyre giving 50 minutes or around 22 laps of the circuit.

Temperatures came up in a similar fashion. Overall temperatures after run were around 6 to 8 degrees hotter.

Driver comments

Within 3 corners the first driver had radioed to the pits that they had come on and “sign him up.”

Comments being, they came on very quickly and were just “far more stable and better” allowing power to be applied earlier. The driver was very happy to stay out for the 25-minute session. The second driver reported the same with particular comments about braking, that “it felt like the tyre squishing into the ground.” And that it was better than the H1 tyre. Both drivers were highly excited by the drive and reported no drop off at all in performance.

Fastest lap was reported at 2:12.5. This time would have put them second in their CSCC class with the only faster car being the ex BTCC Halfords Honda Integra DC5 driven by Andrew Jordan. Comments made by phone today have indicated that in other race clubs they compete in it would put them on pole by over 3 seconds.


So to sum all that up, you pick a tyre on the attributes that it gives to the car and driver for a particular set of circumstances. Weight is not an attribute you would assess as it is a by-product of the construction to give you those attributes and not a valid or assessable attribute it its own right.
 

NickD

Gold Member
While I am on this. The Nitto Nankang "test" is one of those things that tries to over analyse and ends up creating "Internet knowledge"
Comparing a used tyre against a worn tyre is never valid. This is wronger than a wrong thing in wrong custard!
"The car has been running a set of 205 40 17 Nitto NT 01's for the past two years. These are now well worn, but are still putting down good lap times, the car has been steadily getting quicker over the past two years on the same tyres. So the NT01's will be the point of comparison for the Nankangs"
You would never ever see Lewis Hamilton saying "we found some tyres that did the fastest lap at Bahrain last year and we are going to try them against the new soft tyre"
Equally shore hardness tests of tyres is never good. The readings creep as the rubber gives way. Most new tyres, road or track are pretty much the same and even if they did get a reading, all it says is the Nitto are old and hard.
Tread wear, my favourite hate, is an American road driving life test and not a measure of grip. The test produces results at road temps. Any decent track tyre will not be in it's operating temp window at this point and still be glassy. Certainly any proper track tyre would want to be around 80 deg. It is not for no reason race tyres are taken off wearing gloves.
Weight is irrelevant to performance. When you read someone on the internet saying a tyre has soft sidewalls and they understeered into the wall. They don't say it would not have happened it the tyre had been lighter, they say it had soft sidewalls, or the tread delaminated. When someone says a SP Cup tread wore quickly and was not very good, they don't put it down to being too heavy or light, they just say how it drove and how it wore. If they liked it or not.
 

Dave W

Paid Member
I swapped out a set of R888Rs for some Yokohama A052s. The Toyos were finished and weighed the same as the new Yokos. I only weighed them because I was curious and if I've saved 4-6Kg on the car (which I have comparing new with new) then great.
Performance wise, the 52s have been much faster on each of the hills I've raced since swapping and miles quieter on the road.