| Author | Message | ||
| Jon P. Kofod (95f355c)
Member Username: 95f355c Post Number: 299 Registered: 8-2001 |
Luigi, Yes the PZero Corsa and the Sport Cup tire are R compound tires. R compound is a term used in the US to denote a track/competition tire that can be driven on public roads. Regards, Jon | ||
| Luigi Gatti (Luigi)
Junior Member Username: Luigi Post Number: 56 Registered: 10-2001 |
Thanks for all the info(very informative Jon). Are R compounds the same as P Zero Corsa or Michelin Sport Cup tyres. I don't think we have Kumhos or Hoosiers here in Europe. | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 231 Registered: 3-2001 |
Giang....those are some great shots....looks like you had a really good time! | ||
| Giang Hoang (Spidersense)
New member Username: Spidersense Post Number: 29 Registered: 10-2002 |
Thanks Jon, but if possible, I will have to have my girlfriend take my spot. She's been dying to go. We will be there even if we don't get rides. Fun.. Matt, I have some pictures of that last event. http://members.cox.net/ferrari328gts/ | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 230 Registered: 3-2001 |
Yeah Jon, I would be very interested to see what happens on the 22nd. Dont forget, the weather will suck, even if it is dry. Pushing it then, is a relative concept. Be careful pal. I think the trucks are done for the season. There might be a couple of them out there, but for the most part, they are done. By the way, that Radical mpeg you sent to me....Im really thinking about it. 252 hp in a 1,000lb racecar...= 756hp in a 3,000lb racecar....hmmmmmm. THAT WOULD BE OUTRAGEOUS!! Also, very interesting that conversation you had re your challenge car. Let me know what happens! | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 2756 Registered: 12-2000 |
Jon is right on, I just want to back him up. I would never run R compound DOT's on the street. They would only last 1,000 miles, they are noisy, they throw rubber on the car, they take awhile to heat up and get traction on the street. For anything but the most serious track racers in challenge cars, I would only recomend the R compound tires. Here's my experience with the various brands... 1) Toyo RA-1's (last longest, but half second slower per lap than Kuhmo and at least one second slower than the Hoosiers) This would be TWS. I have 4 race weekends on my Toyos and putting another on. That's 16 track sessions. 2) Kuhmo V700's (good grip, last about 60% of Toyo's) 3) Hoosiers (best DOT grip, but last maybe 30% of Toyo's) DOT R tires are much closer to slicks than high performance street tires are to DOT R's. DOT R tires have a tread rating of under 60. Most performance tires have a tread rating starting at least 120. About warming DOT tires up, doesn't take long. We start cold with one slow pace lap before a rolling start in SCCA. I'll do the little back and forth and speed and brake for half the lap. The tires hold the first turn, but I do notice small additional improvements until it levels off about 3 laps in. | ||
| Jon P. Kofod (95f355c)
Member Username: 95f355c Post Number: 298 Registered: 8-2001 |
Thanks for the compliment Matt. Homefield has it's advantages though I think your running the same laptimes at Summit. The Glen is a different story, your on another planet there. I checked Ike Nielson's lap times for his E36 M3 GTR at the last BMWCCA Tirerack Club race at Summit a few months back (he finished 3rd overall) and he was turning 1:22's with perfect weather so I think you and I are running closer to 1:20-1:19. I know I was at least a second or so quicker than Ike at the last event, though I have no way of knowing if his car was running right. Makes you wonder what we could do with a 650 hp Trans Am car. Those cars turn 1:17's in the Regional and Nationals (SCCA). I think we could beat those times. I am getting a Hot Lap Timer installed for the last event next week. I have one in the BMW and it takes away the manual error of playing back laptimes on a camcorder. Will hopefully have good weather on the 22nd and will then see if 1:18 is attainable and if I really did a true low 1:19. It's practice day right before the ERMA Race weekend so I am hoping your NASCAR buddies show up with their trucks. Giang, you are welcome to come out again on the 22nd. I have two rides booked but you could go out one session if you like. Regards, Jon | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 229 Registered: 3-2001 |
Thanks Giang...I meant that in jest. But for the record, I was not up to snuff that day. No real excuses. | ||
| Giang Hoang (Spidersense)
New member Username: Spidersense Post Number: 27 Registered: 10-2002 |
Matt, of course I meant it as a compliment. And what a day at the track! Thanks so much Jon. I enjoyed the ride even more than I enjoy your posts! Even if I don't get a ride, I can't wait to see Matt and Jon go at it again on the track. Jon, I've printed pics of me and your car to give out to my family/friends who wanted them. Now all I have to do is post one in my profile and tell everybody it is mine.  | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 227 Registered: 3-2001 |
You mean when you were screaming around the track, and I was trying to keep up? | ||
| Jon P. Kofod (95f355c)
Member Username: 95f355c Post Number: 295 Registered: 8-2001 |
Matt, Giang mean it as a compliment to your fast driving. I gave him a ride in my Challenge car after lunch at the Trackmasters event last month at Summit Point. He was also watching from the stands when you, Chris and I were running together. Regards, Jon | ||
| Mark Freeman (Mrpc12)
Junior Member Username: Mrpc12 Post Number: 95 Registered: 11-2001 |
Jon: Thanks for your post. Great information. I learned allot about tires without having to buy any! | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 225 Registered: 3-2001 |
Giang...as I'm not sure exactly how to take your comment of me on the track...thanks (I think)! | ||
| Giang Hoang (Spidersense)
New member Username: Spidersense Post Number: 25 Registered: 10-2002 |
I've seen Matt on the track, he NEEDS slicks. I drive my car mainly on the streets, but I have run the Kumho Victoracer V700 and the Toyo RA-1. Both are R compound and the Toyos should more than double the Kumho's lifespan. The Toyos are much more street like and manageable, if you plan on driving on the steets most of the time. | ||
| Jon P. Kofod (95f355c)
Member Username: 95f355c Post Number: 292 Registered: 8-2001 |
Both Matt and Lawrence hit it pretty much on the money. I use slicks on the Challenge car and use R rated compounds on the BMW M5 Club Racer. I have tried almost all the R type tires including the Kumho Victoracers and Ecstas as well as the old BFGoodrich R1 G-Force tires and the Hoosiers. Keep in mind that I don't use them on the street and always get them shaved to 3/32nds. There would indeed be a trade off on both the track and street. Just take a look at F1 where those tiny four grooves on their slicks make a huge difference in grip (one they have largely overcome through the use of aerodynamics). No R compound tire will ever grip like a true slick. An R compound is somewhere in betweeen a street tire and a slick. Although not a slick, I would say an R compound is closer to a slick than a street tire, but there is still a huge difference in grip levels. In terms of wear, most slicks (PZero slick) will last only half as long as the average R compound. The only exception being the Hoosiers which only last marginally longer than a slick. Getting back to the street issue, you could in theory use an R compound on the street if it is not shaved. A shaved R compound would lose it's treat pattern fairly quickly and you would not be able to drive them in the rain. The other issue you would have to deal with is constant fiddling with the tire pressure. R compound tires usually need significant heat to get up to correct tire pressure, same as a slick. Your basic street tire is inflated to anywhere from 36-43 pounds of pressure and kept there on most cars. At the track (depending on the weight of your car) you typically start out with very low tire pressure (30-32 pounds for a R compound) and heat them up on the track which adds another 6-8 pounds of pressure. Slicks need even lower pressure. The base line advice from Pirelli for the PZero slick is 23 pounds cold in the front and 22 cold in the rear. This would create a dilema as you would typically not drive hard all the time so if you set the tire pressure at what most manufacturers recommend for an R compound COLD you would have too low of a tire pressure for normal street use. The flip side is that if you added more air pressure to compensate for this you would have way too much air pressure when driving hard and heating up the tires and this would cause premature wear. Other issue is that in street driving with cold outside temperatures there would be little or no grip in normal street driving. If you live in warm climate you might be able to get away with a unshaved R compound and low tire pressure but I am not sure how well it would work. As for grip at the track the R compounds are the same as any other tire. The more grip you get the more wear takes place. The Hoosiers on my BMW are worth nearly 1 1/2 seconds a lap on a 2.5 mile road course over the Kuhmos. The Hoosiers will normally last three days at most (10-12 heat cycles) while the Kumhos will last nearly twice that. I have been told that the Toyo and Yokohama R compounds last nearly twice as long as the Kumhos but again have less grip. I really can't see exploiting the performance potential of a shaved R compound on the street. It is possible that an unshaved R compound might be possible but not a shaved tire. The other item to be aware of is the proper way to heat cycle. Most racers who buy their tires from Tirerack don't get them heat cycled at Tirerack. The machine they use can't really replicate accurately the heat cycle effect a tire will get on a specific car. For a while I had my tires heat cycled at Tirerack, but I have found that I get an extra day out of my Kumho's if I heat cycle them myself by putting them on my car and doing one light session and thenm taking them off for a day or two. With the Hoosiers this didn't seem to matter as they lasted about the same no matter who heat cycled them. I have never run true slicks on my BMW nor have I ever run R compounds on my Challenge car so I can't really give you solid numbers on the difference between a true slick and a R compound but a seat of the pants feel indicates to me that an R compound might rate around a 7 or 8 compared to a slick tire (1 being a street tire and 10 being a true race slick). I would put the Hoosier near 8 and the other R compounds at a 7). I think the main benefit of R compound tires at the track is cost, wear and a good stepping stone to move from street tires to more performance oriented tires. Going from a street tire to a slick would be a recipe for disaster so R compounds offer a good compromise between the two extremes. Hope this helps! Regards, Jon P. Kofod 1995 F355 Challenge 1988 M5 Club Racer | ||
| Lawrence Coppari (Lawrence)
Member Username: Lawrence Post Number: 388 Registered: 4-2002 |
Furthermore, regarding R compound tires, you have to get them warm else risk a spin. The Kuhmo tires I was talking about are R rated. How many times have I seen drivers spin or wreck cars the first run of the day when tires are cold.....many times even with experienced drivers. | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 224 Registered: 3-2001 |
Viken, I dont have the numbers (Jon Kofod is usually good for that), but I can assure you that an R compound tire will always (in dry conditions) underperform a slick. There are noticable and significant differences on the track, and it would not be possible for an R compound to keep up with a slick. If someone does not modify their 355 or 360, is it my understanding that you think it would be better if they used an R compound tire? If that is your contention, it is incorrect. As far as street use, why would someone want to use an R compound tire? Its not like anyone can do such agressive driving that it would necessitate a better tire than what the car comes with. And it is less comfortable as well. | ||
| Lawrence Coppari (Lawrence)
Member Username: Lawrence Post Number: 387 Registered: 4-2002 |
Has anyone tried Kumho Victoracers? They are street legal. I use them for track events on my Porsche. They don't cost too much, they grip almost as well as Hoosiers but last longer. They have a tread of about 5/32 inch when new. You should heat cycle them once before using. | ||
| Viken Bedrossian (Vikenb)
Junior Member Username: Vikenb Post Number: 209 Registered: 5-2001 |
>> The DOT approved track tires are not such a good compromise, for either the track or the road. They do not offer such good grip on the track (I mean it is fun....-I call it iceskating- but it's not good if you are serious on the track), and they are not comfortable for everyday use either. If you spend time on the track, I would suggest buying another set of rims, and putting slicks on them. << I am not sure I completely agree with that. Some R-compound tires offer exceptionally better grip than most maximum performance street tires while lasting quite a bit more than slicks. Some are also quite comfortable on the street. If you do not have a highly modified car, an R-compound tire will likely perform better overall than a racing slick. | ||
| Luigi Gatti (Luigi)
Junior Member Username: Luigi Post Number: 55 Registered: 10-2001 |
Thanks Viken! | ||
| Viken Bedrossian (Vikenb)
Junior Member Username: Vikenb Post Number: 208 Registered: 5-2001 |
Luigi, Both the P-Zero Corsa and Pilot Sport Cup are excellent tires. Unfortunately, the Michelin is not available in 360 sizes either. At least, not yet. Here is some info on the Cups: http://www.michelinman.com/catalog/tires/pilotsportcup.html | ||
| Matt Karson (Squidracing)
Junior Member Username: Squidracing Post Number: 223 Registered: 3-2001 |
The DOT approved track tires are not such a good compromise, for either the track or the road. They do not offer such good grip on the track (I mean it is fun....-I call it iceskating- but it's not good if you are serious on the track), and they are not comfortable for everyday use either. If you spend time on the track, I would suggest buying another set of rims, and putting slicks on them. | ||
| Luigi Gatti (Luigi)
Junior Member Username: Luigi Post Number: 54 Registered: 10-2001 |
I'm thinking of going for a set of semi-slick road/track tyres for my next set of rubber. I know Pirelli and Michelin manufacture this type of tyres, the Pzero Corsa and Pilot sport Cup(or a similar name). I know the Corsa is not made in the 360's sizes, but I have no info on the Michelin Cup, does anybodyknow a link where I can find any info on this rubber and possibly the sizes? Does anyone have experience with semi-slicks? |