BFG R1-S Test and Tune
May 6, 2013, 01:10 PM
#91
Evolved Member
Thread Starter
Join Date: Mar 2004
Location: Dallas
Posts: 535
Likes: 0
Received 0 Likes
on
0 Posts
My car is always dual driven on R-comps, and bagged on cooler days. Most event these days though I'm running street tires and save the r-comps for testing and big races.
I'm on 10" wheels, but have about a 3/4" pull up front and 1/2 in the back. R/Ts rear trailing links too so no rear spacer. If it doesn't fit right, Ill just have my guy come over and roll the fenders more
.
Any advice on ballpark hot pressures? I'll dial it in on a skidpad but would be easier know where to start.
I'm on 10" wheels, but have about a 3/4" pull up front and 1/2 in the back. R/Ts rear trailing links too so no rear spacer. If it doesn't fit right, Ill just have my guy come over and roll the fenders more
. Any advice on ballpark hot pressures? I'll dial it in on a skidpad but would be easier know where to start.
I only caution you because of your climate. These are hot weather/summer tires. There is no doubt they are more durable than hoosiers. But you will sacrifice at least you 1st run if not both of your 1st runs.
May 6, 2013, 01:20 PM
#92
On 9.5's I have been running 37-38 psi. Above that they get skatey real quick. I have ran lower but they did roll over too much.
I only caution you because of your climate. These are hot weather/summer tires. There is no doubt they are more durable than hoosiers. But you will sacrifice at least you 1st run if not both of your 1st runs.
I only caution you because of your climate. These are hot weather/summer tires. There is no doubt they are more durable than hoosiers. But you will sacrifice at least you 1st run if not both of your 1st runs.
Do you under-pressure your tires on the first run? Cold so less grip and less roll, but on the kumhos they built heat quicker. If I think I'll gain 4psi in a run, I'll start that run 3-4psi low. I only do it on the first run or 2, but it's helped in the past.
May 20, 2013, 10:00 AM
#93
Evolved Member
Thread Starter
Join Date: Mar 2004
Location: Dallas
Posts: 535
Likes: 0
Received 0 Likes
on
0 Posts
So we ran a brand new set of R1's and a brand new set of A6's yesterday. Scrubbing them in for the Spring nats/pro this weekend.
Interesting results to say the least. Link is here http://texasscca.org/2013_solo_resul..._final.htm#ASP
Blanton
39.978 - BFG
38.449 - BFG
38.407 - BFG (parked it for .5 seconds near end of course so theoretical 37.9xx)
37.073+1 - Hoosier (turned in early on a non critical cone)
37.965 - Hooiser (threw it away near the end again, segment times indicate low 37)
JFO
38.480 - BFG
38.145 - BFG
37.740 - BFG
37.418 - Hoosier
37.168+1 - Hoosier
Both sets were brand new with zero heat cycles and no heat cycling done. Wheels were 18x9.5". Tires were 285/30/18.
37psi on BFG
40 and then 38 on Hoosiers.
Surface was sealed asphalt, relatively smooth. Temps were in the low 80's, sunny and windy.
Of note, we tested a front splitter today also.
Here are my observations. The BFG's were much easier to drive all around. The feedback was more direct and the adhesion limit was very easy to detect. The car did not want to slide at all. Grip off the line was also noticeably better than the hoosiers.
The hoosiers definitely could be slid around more. And were easier in general to evoke wheelspin both off the line and during maneuvers on course. Where the BFG just stayed planted. Indicating that the BFG's may have more longitudal grip. Or even more grip all around. Yet they were ultimately slower.
My take overall on hoosiers is that they like to be driven with little to no slip angle. "Tight and tidy" if you will. However, at this event they were faster with more slip angle than I typically drive.
This was Blanton's 1st time on fresh rubber and 1st time on Hoosiers. He dropped significant time on his 1st run on the hooisers over the BFG's that I cannot ignore.
We will reserve final judgement for this week once we are in Lincoln. But interesting data point nonetheless.
Interesting results to say the least. Link is here http://texasscca.org/2013_solo_resul..._final.htm#ASP
Blanton
39.978 - BFG
38.449 - BFG
38.407 - BFG (parked it for .5 seconds near end of course so theoretical 37.9xx)
37.073+1 - Hoosier (turned in early on a non critical cone)
37.965 - Hooiser (threw it away near the end again, segment times indicate low 37)
JFO
38.480 - BFG
38.145 - BFG
37.740 - BFG
37.418 - Hoosier
37.168+1 - Hoosier
Both sets were brand new with zero heat cycles and no heat cycling done. Wheels were 18x9.5". Tires were 285/30/18.
37psi on BFG
40 and then 38 on Hoosiers.
Surface was sealed asphalt, relatively smooth. Temps were in the low 80's, sunny and windy.
Of note, we tested a front splitter today also.
Here are my observations. The BFG's were much easier to drive all around. The feedback was more direct and the adhesion limit was very easy to detect. The car did not want to slide at all. Grip off the line was also noticeably better than the hoosiers.
The hoosiers definitely could be slid around more. And were easier in general to evoke wheelspin both off the line and during maneuvers on course. Where the BFG just stayed planted. Indicating that the BFG's may have more longitudal grip. Or even more grip all around. Yet they were ultimately slower.
My take overall on hoosiers is that they like to be driven with little to no slip angle. "Tight and tidy" if you will. However, at this event they were faster with more slip angle than I typically drive.
This was Blanton's 1st time on fresh rubber and 1st time on Hoosiers. He dropped significant time on his 1st run on the hooisers over the BFG's that I cannot ignore.
We will reserve final judgement for this week once we are in Lincoln. But interesting data point nonetheless.
May 20, 2013, 10:30 AM
#94
Im wondering if you need a bit of balance change with the BFGs. I remember back when I went to the hoosiers from kumhos that I went slower because the balance was all out of whack. Lots more grip, but no rotation.
Itll be another couple weeks before I test the BFGs so I still dont have any idea how my car will like them compared to purple crack.
Itll be another couple weeks before I test the BFGs so I still dont have any idea how my car will like them compared to purple crack.
May 20, 2013, 01:03 PM
#96
Evolved Member
Thread Starter
Join Date: Mar 2004
Location: Dallas
Posts: 535
Likes: 0
Received 0 Likes
on
0 Posts
Im wondering if you need a bit of balance change with the BFGs. I remember back when I went to the hoosiers from kumhos that I went slower because the balance was all out of whack. Lots more grip, but no rotation.
Itll be another couple weeks before I test the BFGs so I still dont have any idea how my car will like them compared to purple crack.
Itll be another couple weeks before I test the BFGs so I still dont have any idea how my car will like them compared to purple crack.
37 is as low as I have gone based on tire chalking. I've gone as high as 40 and found them to be undriveable at that pressure. I expect pressures would be lower on a 10 or 10.5" wheel. But I don't have widths that size in the proper offest or enough caster to fit them.
Last edited by ratt_finkel; May 20, 2013 at 01:19 PM.
May 20, 2013, 02:43 PM
#98
We're also talking about autocross here... I'm not sure if you're talking about a track event or autocross.
May 20, 2013, 03:20 PM
#100
Evolved Member
Thread Starter
Join Date: Mar 2004
Location: Dallas
Posts: 535
Likes: 0
Received 0 Likes
on
0 Posts
I was just basing that on what I've heard from the people running them at local events. I've heard that due to the stiff sidewall the pressures they like are more like a Kumho V710.
We're also talking about autocross here... I'm not sure if you're talking about a track event or autocross.
We're also talking about autocross here... I'm not sure if you're talking about a track event or autocross.
May 20, 2013, 05:08 PM
#102
37 is as low as I have gone based on tire chalking. I've gone as high as 40 and found them to be undriveable at that pressure. I expect pressures would be lower on a 10 or 10.5" wheel. But I don't have widths that size in the proper offest or enough caster to fit them.
