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Anyone use Pirelli 315/705/19 slicks on their GT350R?

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I'm looking at getting some scrubs for the upcoming track season. Another GT350 driver in my region has successfully used 305/690/19 tires, but apparently they are no longer available. Ferrari Challenge is now using 315/705/19 slicks. Rear fitment should be OK, but not sure about the front. Has anyone used these sizes?
 
I think there's wiggle room, but in the end I don't think it will matter much. I don't expect to be competitive against the Hoosiered and aero'ed Corvettes in my class that are 600 pounds lighter. TT is a safer and faster group with fewer restrictions than HPDE, so TT it is.
 

Bill Pemberton

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Oh, I know ,it is just that the point .3 factor when using Pirelli slicks could move you right up into TT1 instead of TT2.
 
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Steve, you really think TT is safer than DE?

I got offered to get bumped into 4 but I didn't want to run with the TT guys out of fear, they have actual numbers they are chasing.
 
Austin,
I know most of the drivers in TT, and I will usually have a discussion with the drivers in my class prior to the first session to ensure I stay out of their way, or otherwise do what I can when they are in the middle of a flyer for points/contingencies. And this season I also will be running for contingencies. Also, since grid is determined by lap times in TT as opposed to random gridding in 3/4, there is less likelihood of interfering with other driver's flyers (except for Val in his mad stronk Corvette of doom, he laps everyone.)
Group 3/4 is often pretty crowded, and I don't know many of the drivers, so from my perspective there is less unpredictability in TT as well.
I also have the option of running in 3/4 if I let the group leader know and it's less crowded than usual.
 
revisting this thread 3 years later. Just wondering if anyone has successfully run 315/705/19 pirelli slicks on a 350 without any rubbing In the front? My tire guy is saying I can with a minimum of 3 degrees camber but I‘d love to hear from someone who has actually done it. Thanks for any help
 
I ran these tires last year on 19x11 ET52 wheel with 25mm spacer. They barely rub on the rear inner fender cover when turning. I really did not like these tires, grip was fine, but I was able to run faster more consistent laps on Toyo 295s. I feel like these tires are to tall for this car, so you are not rolling through the RPM's like you are with a shorter tire, and with this being a bigger tire it will weigh more. I would have really like to run the 690 sidewall to see if it would have been faster. It just sucks there are not many options for a 19" takeoff, looking back I would have gone a different route. I would invested in smaller front calipers to run 18" wheels square to get more options, but now already invested in two sets of 19" wheels.

I ran Pirelli take offs on my Boss, and they were great so I am not meaning to talk bad on these Pirelli take offs. My opinion is that I feel the car would benefit more from a shorter/lighter tire. Maybe if the car had more power over stock it may make the difference too, so if you a few power bolt on's these may work out for you.
 

Bill Pemberton

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Heh, neighbor, you do have a great choice for 2022, just spend the bucks for a set of Hoosier R7s, because with the repaving of MPH ( Motorsport Park Hastings) the two tracks nearest you are there and Topeka. You already are aware Topeka is so easy on tires one can get a weekend or two of additional tirewear and Hastings now has a very similar surface. If you liked the Toyos, you will be blown away by the Hoosiers - I know I am switching back for 2022.
 
I ran these tires last year on 19x11 ET52 wheel with 25mm spacer. They barely rub on the rear inner fender cover when turning. I really did not like these tires, grip was fine, but I was able to run faster more consistent laps on Toyo 295s. I feel like these tires are to tall for this car, so you are not rolling through the RPM's like you are with a shorter tire, and with this being a bigger tire it will weigh more. I would have really like to run the 690 sidewall to see if it would have been faster. It just sucks there are not many options for a 19" takeoff, looking back I would have gone a different route. I would invested in smaller front calipers to run 18" wheels square to get more options, but now already invested in two sets of 19" wheels.

I ran Pirelli take offs on my Boss, and they were great so I am not meaning to talk bad on these Pirelli take offs. My opinion is that I feel the car would benefit more from a shorter/lighter tire. Maybe if the car had more power over stock it may make the difference too, so if you a few power bolt on's these may work out for you.
Thank you sir for the feedback. You brought up a lot of what I was thinking with a taller and heavier tire. Like you, I really wish we could run a 18” inch wheel and run the correct tire. I have been running supercar 3r’s and really like them but I’m not only getting 3 days out of them at $1400 a set. My thought is the pirelli take offs would last just as long at under half the price? Maybe I’m optimistic about that? Also I wasn’t aware of a smaller brake kit, and I have probably $1500 in new brake pads sitting on the shelf that I’m sure wouldn’t work.
 
Heh, neighbor, you do have a great choice for 2022, just spend the bucks for a set of Hoosier R7s, because with the repaving of MPH ( Motorsport Park Hastings) the two tracks nearest you are there and Topeka. You already are aware Topeka is so easy on tires one can get a weekend or two of additional tirewear and Hastings now has a very similar surface. If you liked the Toyos, you will be blown away by the Hoosiers - I know I am switching back for 2022.
Yea I hear ya, but last I looked the Hoosiers were around $550/tire so $2,200/set. Take offs were running me around $150/tire so $600/set so I could get 3 sets of take off's for a set of new Hoosiers. Since I just go do it for fun no need to run a certain tire so still think take offs would be cheaper. Without having a good selection of take off's I may be buying new though.....
Thank you sir for the feedback. You brought up a lot of what I was thinking with a taller and heavier tire. Like you, I really wish we could run a 18” inch wheel and run the correct tire. I have been running supercar 3r’s and really like them but I’m not only getting 3 days out of them at $1400 a set. My thought is the pirelli take offs would last just as long at under half the price? Maybe I’m optimistic about that? Also I wasn’t aware of a smaller brake kit, and I have probably $1500 in new brake pads sitting on the shelf that I’m sure wouldn’t work.
I would need to look on our vendor page to see who on here supplies these calipers, but the thread above goes over the smaller caliper. Just a couple months ago someone on here had a used set on here for $2,500 and I really debated on getting them. Pair those up with the new lightweight Apex wheels and you are set.
On my Boss I felt the used Pirelli's stood up pretty good compared to a new set of Hoosiers, I probably got the same amount of life out of both and same if not faster lap times. I did cord 2 of the used Pirelli's 705/19s within 5 sessions of using them on my GT350. I was rotating them and front camber was -2.8 and rear was -2.5, so not sure if I was just overdriving the car or if the take offs did not have as much rubber on them. Previous I always got great wear.
Like I said this is just my opinion, if I could start over I would have gone with the smaller caliper and went with 18" wheels to get more tire options and possibly less rotational mass. May be doing this in the future, just right now sticking all my money into house upgrades.
 
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@blacksheep-1 Do you have a recommendation on hot pressures/camber for these Pirellis? Not sure I'm reading my stuff right, but it seems like they perform better with more camber than my temps say I should be running. Probe says I should be running -3.2 up front, but lap times like all I can give them (-3.7 or so)
 
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@blacksheep-1 Do you have a recommendation on hot pressures/camber for these Pirellis? Not sure I'm reading my stuff right, but it seems like they perform better with more camber than my temps say I should be running. Probe says I should be running -3.2 up front, but lap times like all I can give them (-3.7 or so)
The whole temp thing can be confusing, I know common knowledge says that temps across the face of the tire should be similar, to determine which inflation/camber, etc is best, while that might work in an open wheel car, (with all due regards to Carrol Smith, he was an open wheel guy) but it really doesn't apply to the cars we run, these cars need lots of suspension movement to plant the tires. So the tire temps will be all over the place, especially when a car runs down the straight with a ton of camber, then heads to pit lane. Again, and with these sidewalls, and car weights, a car that might read 210 on the inside and 195 on the outside with 175 in the middle, may not be an inflation issue, it simply means the car has a lot of camber, runs down the straight, then , using mechanical grip, plants the tire in the corner and it "rolls under" a bit.
I would go with the lap times if it were me, but I would be very cautious about over heating the inside of the tire,, say ball park, 250 max.
 
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The whole temp thing can be confusing, I know common knowledge says that temps across the face of the tire should be similar, to determine which inflation/camber, etc is best, while that might work in an open wheel car, (with all due regards to Carrol Smith, he was an open wheel guy) but it really doesn't apply to the cars we run, these cars need lots of suspension movement to plant the tires. So the tire temps will be all over the place, especially when a car runs down the straight with a ton of camber, then heads to pit lane. Again, and with these sidewalls, and car weights, a car that might read 210 on the inside and 195 on the outside with 175 in the middle, may not be an inflation issue, it simply means the car has a lot of camber, runs down the straight, then , using mechanical grip, plants the tire in the corner and it "rolls under" a bit.
I would go with the lap times if it were me, but I would be very cautious about over heating the inside of the tire,, say ball park, 250 max.

Did Carroll say that temps should be even across the tire? I'm going to need a quote on that one. I will say, there's a couple things to take into account concerning the 'Old Man'.

He spent time with every sort of car, from Formula Ford to Endurance prototypes. He was on the GT40 program, among others. The whole open/closed wheel thing doesn't really matter. The tire doesn't know the difference. At different times I've had people tell me I couldn't do one because of experience with the other. I've never understood why.

Most of his work was on bias ply tires. They tend to run much less camber than radials, so that would naturally make his temperature spread recommendations lower across the tire.

The older I get, the more I'm impressed with what Carroll did. He got all sorts of stuff wrong, but we only know this because he was one of very few of his era (or any) to actually put his thoughts in print. He started writing in the mid-70's and stopped in the mid-90's. He didn't have the data and computer analysis we have. Data systems were still pretty new when he retired from pro racing. It was all just pencil and paper. It's no real surprise he got some stuff wrong, but it's freakin' amazing at how much he got right!
 

Bill Pemberton

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TeeLew,
You will find we are lucky to have the " Old Man " ( Blacksheep 1 ) because like Carroll he has worked on all kinds of cars/teams as their Tire Guru and since there are numerous National Championships behind alot of the Teams he has worked on, we can consider him the Professor of Rubber Race Donuts. Like Carroll worked with bias ply, BS1 is just biased , but he does know his radials, ha. Not taking anything away from the really great note you wrote , I just wanted to make sure you were aware we are lucky to have an Old Man who speaketh race rubber in many languages ( French - Michelin, Italian - Pirelli, Hoosier - Midwestern Merikan, German - Continental ) and his thoughts have been beneficial to many of us.
 

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