11 replies to this topic

[topgear3793]

Hi all,

 

For those with experience on both current competition tires, how much faster are the Hoosier's than the Toyo's?

 

Given your average 2 minute track, do people see 0.5sec? 1sec? 1.5sec? nothing?

 

Also, air temperature? For every ten degrees farenheit how much does lap time vary? Are we talking a tenth or half a second?

 

Appreciate any insight here.

 

Best,

Matt

[Ron Alan]

You can find these answers by searching completed races on mylaps. Look at the results for the 2014 SCCA Majors(April) at Thunderhill and then 2015 Regional SCCA April event at TH...same track...time of year...some of the same people...SM7 vs RR. 

 

Or you can look back in your texts you asked me the same question

 

Or using Mark as a benchmark...I think about .5 at Laguna, .8 at Sonoma and .8 at TH?(memory here). Similar difference for faster guys but more spread for mid-pack guys(I think the initial grip of the Hoosier is more confidence inspiring). 

 

But in the end...air temp, sunshine, overcast, track temp, track rubber, wind direction, set up, etc make it really hard to compare times from different days...let alone different tires!!

[Danny Steyn]

But in the end...air temp, sunshine, overcast, track temp, track rubber, wind direction, set up, etc make it really hard to compare times from different days...let alone different tires!!

 

^^^^This!^^^^^

 

Barber is a handling track and it is all about grip.

 

In August 2013, running Hoosier SM6's I set the SCCA SM lap record at Barber at 1:46.735.  The SM6's were the hero tire with the most grip we have ever had. 

 

Then in February 2015 on a really cold day, running Toyos, I was able to get into the mid 1:44's in qualifying, and set the new NASA SM lap record 1:45.719 (almost a full second faster than on the stickiest Hoosiers)

 

And then yesterday, in temperatures over 100 degrees, running on Hoosier SM7's I was able to almost equal my SCCA lap record, and ran 1:46.798.

 

So while on the same day, Hoosiers will generally be faster than Toyos, as Ron said, comparing lap times from different days is often going to be misleading unless you know all the conditions

[Todd Green]

Also, air temperature? For every ten degrees farenheit how much does lap time vary? Are we talking a tenth or half a second?

 

Figure roughly a 1% change in power for every 10* (assuming of course it doesn't get so hot that your car starts pulling timing etc.)  See this page if you want to get more exact calculations that are used in dynos.  As an example the track record for the 3 mile course at UMC is a 17.6 (at around 60*) set in May 2013.  Times later that year in Sep at the National Championship were in the low 19's when the temps were in the mid 80's (roughly estimating looking up temps in almanacs).  The outer loop has long straights and really rewards power.  If you have a more handling-based track of course the differential will be less. YMMV.

[topgear3793]

Thanks guys. Aware it is subjective, just hoping that someone has ran Hoosiers and Toyo back to back, but it is unlikely!

[MPR22]

^^^^This!^^^^^

 

Barber is a handling track and it is all about grip.

 

In August 2013, running Hoosier SM6's I set the SCCA SM lap record at Barber at 1:46.735.  The SM6's were the hero tire with the most grip we have ever had. 

 

Then in February 2015 on a really cold day, running Toyos, I was able to get into the mid 1:44's in qualifying, and set the new NASA SM lap record 1:45.719 (almost a full second faster than on the stickiest Hoosiers)

 

And then yesterday, in temperatures over 100 degrees, running on Hoosier SM7's I was able to almost equal my SCCA lap record, and ran 1:46.798.

 

So while on the same day, Hoosiers will generally be faster than Toyos, as Ron said, comparing lap times from different days is often going to be misleading unless you know all the conditions

Danny,

 

Did you do some testing for the ARRC a few years ago when they were allowed to run either Hoosier or Toyo?  

[Diller]

I tested at Barber last weekend on Toyos (6 heat cycles) and raced this weekend on Hoosiers (2 heat cycles). The weather this weekend was about 10* hotter and I was a little more than a half second faster on the Hoosiers than the Toyos.

 

The interesting thing was the setup changes I made to balance the car on the Toyos was undone to find balance on the Hoosiers. The total amount of grip is not the only difference between the two tires.

[Johnny D]

Different size for one. They both say 205 50/15 but Hoosiers are taller and wider and weigh different, last I checked.

J~

[LarryKing]

May I ask why the differences are important?

[Johnny D]

May I ask why the differences are important?

Yes you may.

J~

[Charlie Hayes]

Toyos can be made very fast, but Hoosier definitely made a race tire. To the limits of DOT on "tread/grooves", size is not true, and the weight is a lot better than the Toyo. You end up comparing apples to oranges, when we want to know apples to apples.

I want to perform this test and plan to this year.

[Danny Steyn]

Danny,

 

Did you do some testing for the ARRC a few years ago when they were allowed to run either Hoosier or Toyo?  

 

Yes I did. The Hoosier (SM6 back then) allowed faster min-speeds through the turns, and the Toyos were faster on the straights. In the end I chose the Hoosier. I have also run Toyo and Hoosier back to back on the same day with the same car at Barber about 7 years ago. Do not remember the Hoosier designation, but it was prior to SM6. Again the Hoosier was faster in the turns and slower in the straights, but faster lap time overall by about 0.2secs on a 1:47 lap.