Best tires and rim size for racing

[bbbart]

He may hit 160 at the braking point but no way he is taking T1 at 150 mph. Outside the rovals I don't see a track in the country where many cars let alone an suv takes a corner at 150 mph. The bigger issue will be if any of the HPDE orgs even let him in.

This is what my local group says about SUVs
"Sport Utility Vehicles: track facilities do NOT allow some sport SUVs to run on track, the simple formula is the factory specified vehicle track width needs to be at least wider than the factory specified height of the vehicle. Track width: the distance between the centerline of two wheels on the same axle. (front axle or rear axle) "

Keep in mind they say FACTORY spec not whatever you have it lowered to the day of the event. I would assume Chin and others are probably in the same boat.

Google says our factory height is 69.8 and track width is 66.9.

Might be tough to find a track, but I'm trying to assess the risk of doing it moreso than committing to that as a goal. The car was definitely not designed to do it, there's no examples to follow, and I've never raced so just making sure I learn as much as possible about the car and listening to all criticism.

It seems possible but some serious changes would have to be made to do it reasonably safely.

Realistically it would never be possible to corner well with air suspension, only in a straight line, but with coilovers things get interesting.

The front end experiences a lot of lift at high speed so a functional front splitter is a necessity, adding a sturdy rear spoiler should make it feel more planted (many existing options look functional), and underbody paneling would tie it all together and reduce a portion of the massive amount of total drag.

Wouldn't be difficult to keep it functional as well.

Replacing all the seats with lightweight seats and removing the back row will save 200-250 pounds. Really don't care for the massage function; just another thing to distract from driving lol

Lightweight battey, light wheels, removing the spare tire and most non-essential accessories should get it down to 4,400 lbs without looking crazy.

4,400 pounds is still no spring chicken, but I can imagine it would be a lot of fun.

 

[boiler662]

Agree on cornering speed for sure. Didn’t even think about the height restriction although it makes sense. Heck, my CTSV was setup for track use lowered with stiff sway bars and it was still a pig in the corners at over 4klbs. ST has to have a higher center of gravity and all the weight. I’ve seen everything from C8’s to hellcats to moms minivan at the 1/4 mile but not on road courses. I believe the non-competition weekend events would allow an ST.


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I'm not talking SCCA or NASA events this is just normal HPDE events with SUV restrictions.

Like you I track my Chevy SS Sedan (Holden Commodore) I know all about throwing 4k pounds around and since I have mag ride I can only run -1.7° camber up front which makes it even harder.....

@bbbart If you have never done any closed circuit driving before I highly recommend finding a class near you, classes are for sure more expensive but invaluable. Learn in something a little more conventional before you take out the ST. Throwing parts at a car first before you know technique generally doesn't work out well. Its not uncommon for guys to show up in 800 hp mustangs and not even finish the weekend because they are in over their heads.

 

[Cruising68]

I'm not talking SCCA or NASA events this is just normal HPDE events with SUV restrictions.

Like you I track my Chevy SS Sedan (Holden Commodore) I know all about throwing 4k pounds around and since I have mag ride I can only run -1.7° camber up front which makes it even harder.....

@bbbart If you have never done any closed circuit driving before I highly recommend finding a class near you, classes are for sure more expensive but invaluable. Learn in something a little more conventional before you take out the ST. Throwing parts at a car first before you know technique generally doesn't work out well. Its not uncommon for guys to show up in 800 hp mustangs and not even finish the weekend because they are in over their heads.

+1 on instruction if little experience. Not only seen people not last the day but also saw people wreck their cars because they didn’t know what they were doing. I had classroom sessions and instructor ride alongs. But to be honest, I learned the most when I asked my instructor to flog my Caddy for a few laps. It was an eye opener in that I learned two things. One was that I was not even approaching the limits of the car particularly braking. Scared the crap out of me when he got warmed up and hit the first few corners. Second was a lesson in momentum and smooth. I was initially more of a hammer the brakes then hammer the gas kind of guy. Learning how to smoothly setup the car for corners so it is setup for early power and exit was a blast. I raced dirt bikes for 20 years before road racing. I found car road racing to have more variables and parameters. When I raced enduros it was mostly reaction. Road racing made me pay much more attention to details.


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[bbbart]

I'm not talking SCCA or NASA events this is just normal HPDE events with SUV restrictions.

Like you I track my Chevy SS Sedan (Holden Commodore) I know all about throwing 4k pounds around and since I have mag ride I can only run -1.7° camber up front which makes it even harder.....

@bbbart If you have never done any closed circuit driving before I highly recommend finding a class near you, classes are for sure more expensive but invaluable. Learn in something a little more conventional before you take out the ST. Throwing parts at a car first before you know technique generally doesn't work out well. Its not uncommon for guys to show up in 800 hp mustangs and not even finish the weekend because they are in over their heads.

Totally agree and I definitely have a lifetime of things to learn on a track. The art of balancing a car during sustained, WOT performance is completely new to me.

It definitely sounds like I'm way over my head here but after getting to know the ST and having years of experience with similarly balanced cars, I'm very confident in my ability to control it at the limit, which is nothing close to what we're discussing here.

I have about 10 hours of experience pushing a C8 just enough to hear the tires, 3 hours in a challenger at the limit, but the vast majority is with a Lexus LS600hL which is an absolute abomination in the weight department at 5,100 pounds at a 50:50 weight distribution. The consequences of mismanaging understeer on that vehicle have prepared me very well for the explorer, the learning curve was very similar to my Lexus with the explorer being a lot better in every category except body roll.

It's a very confidence inspiring vehicle.

 

[bbbart]

+1 on instruction if little experience. Not only seen people not last the day but also saw people wreck their cars because they didn’t know what they were doing. I had classroom sessions and instructor ride alongs. But to be honest, I learned the most when I asked my instructor to flog my Caddy for a few laps. It was an eye opener in that I learned two things. One was that I was not even approaching the limits of the car particularly braking. Scared the crap out of me when he got warmed up and hit the first few corners. Second was a lesson in momentum and smooth. I was initially more of a hammer the brakes then hammer the gas kind of guy. Learning how to smoothly setup the car for corners so it is setup for early power and exit was a blast. I raced dirt bikes for 20 years before road racing. I found car road racing to have more variables and parameters. When I raced enduros it was mostly reaction. Road racing made me pay much more attention to details.


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Thank you for that explanation. Definitely relate to the strategy of hammering the brakes on corner entry and hammering on the way out with the AWD.

I will make a serious effort to rent a similar vehicle to get some track experience. It would suck building this car for track use and not being allowed onto any courses lol

I'm closely following Daren's build and the direction he's going. He's going to have the absolute best-handling ST once it is complete and I believe it will completely redefine people's opinion of the ST at the track.

In retrospect, I regret not buying an Explorer without a sunroof so I'm debating whether it's worth it to throw the kitchen sink at the suspension. I'm trying to determine if it's worth it to squeeze every bit of handling potential out the air suspension or if that's a waste of effort.

 

[Cruising68]

Thank you for that explanation. Definitely relate to the strategy of hammering the brakes on corner entry and hammering on the way out with the AWD.

I will make a serious effort to rent a similar vehicle to get some track experience. It would suck building this car for track use and not being allowed onto any courses lol

I'm closely following Daren's build and the direction he's going. He's going to have the absolute best-handling ST once it is complete and I believe it will completely redefine people's opinion of the ST at the track.

In retrospect, I regret not buying an Explorer without a sunroof so I'm debating whether it's worth it to throw the kitchen sink at the suspension. I'm trying to determine if it's worth it to squeeze every bit of handling potential out the air suspension or if that's a waste of effort.

Keep us posted. Always like hearing about what people do with their vehicles! Not gonna lie, I have been very impressed with the performance of my ST. While I haven’t been on a road course with it, I feel like it is reasonably close to my CTSV in handling which was a much more purpose built performance car.


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