MarkDFW

I am new to R Comps and slicks. Burning through Kumho v710 right now, which are my first R comp. The v710 should last one more HPDE, and then I am going to run a nice set of dunlop slick scurbs with only 1 session that I managed to get my hands on.

What psi should I shoot for? I'm told slicks need less psi than R comps. I would shoot for around 34 - 36 psi on the v710. Should I shoot for 32 hot and start at 24 psi cold for the dunlops?

On a separate note, I only have about -1.2 camber so I will probably chew these up quickly, as I'm told slicks like a lot of negative camber. Doubt there is anything I can do about this. Car is my daily driver so I don't want -3 camber on a street car.

Werks

If you don't want to run a lot of negative camber don't run slicks or R-comps lol, it's as easy as that. With only -1.2 camber you are going to eat up the outside edges of your tires on the track in no time. This is with both slicks and R compounds. Either that or learn how to change your alignment your self so that you can switch between a track alignment and a street set up.

If you do run the slicks I'm not familiar with the dunlops specifically but most seem to like to start of in the low to mid 20's cold and end up in the high 20's to low 30's hot.

MarkDFW

I have actually been surprised by how well the kumho v710 are wearing so far. I have 20 heat cycles and they are still good for another day at the track. And yes, I'm fast considering my car and setup. Plenty of instructors down here would back me up on that. I show my tires no mercy. I was extremely competitive in my first NASA TT event.

I guess I'll find out how the dunlops react to so little negative camber. If I wear them too quickly I may use Pfadts alignment guide and go to their next suggested setting of -1.7 camber. If they need more than that, I'll stick with the Kumho (since they are wearing like iron) or try a Hoosier R6 and see how that wears.

Sidney004

The Dunlops are great slicks, I loved them. 29-30 psi hot. Pull off the track to bleed off pressure as soon as you can to get an accurate reading. You will cord them pretty quickly with so little camber but who cares, you'll have fun doing it. By the way, where are you getting these scrubs, PM me.

vette6aut0x

We have been using the dunlops for three years we have found for best wear negative camber front 2.8, 1/8" out total toe -1.5 rear, 1/8" in total toe. Pressure at ambient should be 22 psi and 31/32 psi hot(180 degrees).

MarkDFW

Thanks. I'm sure I will wear these out quickly with so little camber, but I've heard they are nice tires.

I am slowly converting my car to a track car. A ways down the road I'll get a very aggressive alignment.

Kubs

If you don't want to run a lot of camber, stick with the V710s. As you said earlier they wear great, and are more forgiving with less camber due to the rounded shoulder. Something like a Hoosier A6 or a full slick will require more camber and wear out faster, but will make the car quicker than the V710. If all you are doing are HPDEs and not competing for time or position, stick with the V710. They are awesome for HDPEs.

That being said, the slicks should have a target hot pressure of 28-32psi depending on position on the car, alignment and type of track. The best way to know is to take tire temperatures when coming off the track.

Solofast

Spend a few bucks and get it aligned, you'll save more in one track session in terms of tire wear than you will use up in 20,000 miles on the street. Put in as much negative camber as you can get and set the toe in the front to 1/8 of an inch of toe in and mark the tie rods with stripe of paint or nail polish. When you change to race rubber loosen the tie rod nut and crank in 1 full turn towards toe out on each side. Just set the rear at -1.5 and 1/8 of an inch of toe in.

A setup like that will run for close to 20,000 miles on a set of OE tires, so it isn't as bad as you would think. And yea, you'll wear out the insides first, BFD. You'll double the life of your track tires and you'll save enough to buy two sets of street tires running as much as you run on the track.

Just do it.

MarkDFW

I'm surprised to hear you say that, because I'm told that much negative camber will simply destroy street tires. I put 10,000 miles per year on my 2012 grand sport. It is my daily driver for probably the next couple years. I figured I would only get 20,000 miles on street tires with my existing alignment, which has about -1.2 camber.

If I can get away with that kind of alignment without decimating street tires every 6 months, I will do it. Your point about saving money on track tires is duly noted, as I didn't really think enough about the opportunity cost of running a more conservative alignment costing me money on the track.

I'm hoping someone else will chime in to validate what you are saying. I'm crossing my fingers you are right, it just goes against what I have heard so far.

Here is Pfadt's alignment guide:

http://www.pfadtracing.com/blog/wp-c...-9.12.2011.pdf

I have almost exactly the second from the top alignment.

Pfadt also has this camber kit. Has anyone used this kit or a similar kit and can advise if this is worth it after having an alignment done? Especially considering I still have a street car that will hit the occasional pot hole that could ruin my alignment.

http://www.pfadtracing.com/catalog/p...products_id/52

Kubs

Solo is right about the street miles. What kills street tires in toe not so much camber. I would do what he suggests and mark where 1/8" toe in is, and then have it aligned to zero front toe for the street. I ran with about 2.5 degrees in the front of my C4 for a long time without hurting wear.

63Corvette

Hi Mark, I live in Granbury and run at MSR Cresson, so we are close. I also run Dunlop scrub slicks from (forum vendor) GT racing tires. Note that heat cycled out Dunlop slicks need a LOT of heat in them to work properly. I only paid $50/tire for mine, but they last a long time, and need at least three (3) laps at race speed to come up to temperature in the winter (below 50 degrees F) weather. However, next May or in the summer, they will work MUCH batter. I run about 19psi front and 18psi rear COLD. Did I mention that they are CHEAP?

MarkDFW

I ran NASA TT out at MSR the other week and had a blast.

I have heard they need a lot of heat but once they are hot, the fun begins. And yes, there are good deals to be had on them!

Solofast

I've run that kind of camber for the last 10 years on the street. And Kub's is right, it's toe out that really eats tires. Since it's so easy to set the toe when you change to track tires (it only takes about 2 minutes a side) that there's just no reason not to reset toe when you change tires.

Another thing you can do is when the tires get down to about 1/2 tread is flip the tires on the rims to squeeze a bit more street life out of them.

Race tires are expensive enough that it will pay you to keep them from getting ruined on the edges from not enough camber. If you are running more than 2 HPDE's a year you need to be running max front camber.

WannaC5Z

As I recall I was running about -2.5 camber on the front tires on my Cobra and never had an issue. Given it wasn't a daily driver and I drove only about 1,000 miles per year.

MarkDFW

Thanks for the info guys. I will put this on my to-do list right after I get a race seat and harness, which I badly need.

rustyguns

MarkDFW

Are you using OEM bushings? Pfadt Poly bushings? Spherical? From what I'm ready that can affect how much negative camber you want.

Pfadt has different recommendations depending on your setup:

http://www.pfadtracing.com/blog/wp-c...-9.12.2011.pdf

Thanks everyone for the advice!