Front tire poke at zero toe and zero camber

Joel K

Supporter
Not sure about speed limited, I don’t think that is the case since you can get Michelin Cup 2 tires in run flat or what Michelin calls Zero Pressure.

I’ve had run flats on a C5 Corvette, 2006 Viper Coupe, and my wife has them on her Mini Cooper.

General observation is they do have a more jarring ride and transmit more road noise than non run-flats.

By far the best run-flats were the Michelin Super Sports which were OEM on the viper and those tires were much quieter and less jarring than the Goodyear’s on the Vette. I chose run flats just to eliminate one less potential cause which could require towing the SLC. Also, this will be a street car and perhaps would have chosen differently if I intended to take it to the track.
 
Back in 2009 I attended a World Class Driving 200mph Extreme challenge in Uvalde Texas. The event was at the Continental/General tire tire test track. If you Google earth Uvalde Texas you'll notice a large oval outside of town. It is an eight mile concrete oval surrounded by various other tire testing areas. Long story short the Lambourghini Superleggera we used for the 200mph run had Pirelli run flats. The significance was that ten people were attempting 200 mph. Driver number eight suffered a left rear blowout at approx 180 mph. Because it had run flats he simply eased out of the throttle and coasted to a stop.It was determined the tire failed because of the sustained constant high speeds turns (about 180mph). The car was repaired (minus a few rear facia panels). I was driver number nine and went 201mph. There was so much to this story and the day its too much for this forum.
 

Joel K

Supporter
Well, have my hopes up things will go well. New tires are on their way and found another shop that has the touchless tire mounting system and they also restore aluminum wheels. So even if that one rim needs repair, these guys seem like they can handle the job.

Thanks again for everyone’s input and help.
 
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Joel - what ride height are you taking those measurements at?

I had some poke as well at 0-deg camber/4" front ride height, I run 275 Supersports (non run flat). I'm currently running 4.5" front ride height with ~-2deg camber with the 19" CF10 front wheel. The tuck looks great with this setup but I did wind my lower control arm rod ends all the way in, as you did.

Here's a post all about my initial suspension settings.


I think someone should revisit the recommended tire sizing page, you're not the first person who's had to order smaller tires.
 

Joel K

Supporter
Joel - what ride height are you taking those measurements at?

I had some poke as well at 0-deg camber/4" front ride height, I run 275 Supersports (non run flat). I'm currently running 4.5" front ride height with ~-2deg camber with the 19" CF10 front wheel. The tuck looks great with this setup but I did wind my lower control arm rod ends all the way in, as you did.

Here's a post all about my initial suspension settings.


I think someone should revisit the recommended tire sizing page, you're not the first person who's had to order smaller tires.
Cam, I probably read that page in your blog 50 times! A great write up.

My original ride height was 4.25“ inches with zero camber and had about .8” poke and the fender tops were literally touching the tires. Moved it to 4.75” ride height and about .5 degree angle on the lower control arm which centered the wheels in the side wheel arch nicely and resulted in a small amount of clearance on top of the wheels. My guess is I would need more clearance between the fender top and wheel.

I think the smaller diameter will work better for my body. Leaving the camber at 1.5 degrees the ride height should be about 4.25 with the front wheels centered nicely in the wheel well with more room between the fender wheel top. But this is all a bit in theory since I don have the car on the ground with weight. I am using anti-droop rods to hold the wheels at ride height in the air.

Maybe at some point we add a section to the wiki listing tire specs with a photo of each car for reference.
 
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Johan

Supporter
Joel, I had the same problem with my tires. I was recommended 285/30-19 but they where rubbing on the top arc. Ended up with 275/30-19 and a lot of grinding, the fit ok now. If I would do it all over I would definetly go with 18” in the front.
 

Joel K

Supporter
Joel, I had the same problem with my tires. I was recommended 285/30-19 but they where rubbing on the top arc. Ended up with 275/30-19 and a lot of grinding, the fit ok now. If I would do it all over I would definetly go with 18” in the front.
Thanks Johan, to Cam’s point looks like the Superlite.com page should be updated with better recommendations for front 19” rims. Would have saved a few of us changing the tire choice after initial purchase.
 

Joel K

Supporter
Just received the new tires and they are about an inch narrower which will work out well. Hopefully I can get 4.25” ride height and have them centered nicely in the wheel arches. Also, turned out my comments about the 285/30/19 tires being 12.4” wide was wrong so I updated my comments in the above posts. They are actually 11.4” wide.

The more I think about it, perhaps if I had the 10” wide wheels instead of 9.5“ the offset would be different and the 285s would fit fine. Going to get the new ones mounted and update the thread.
 

Terry Oxandale

Skinny Man
Thanks for the clarification on the size. I couldn't imagine a vendor showing a 285mm section width tire that is actually 315mm wide.
 
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Howard Jones

Supporter
I am currently running -1.5 degrees front and about -1.25 rear. This is very close IMHO for my car, especially considering I intend to go up from 650F 850R about 150 pounds/inch on spring rates ending at 800F 1000R. Remember, less body roll = equals less dynamic camber change and after all that is what the neg camber is on the car to compensate for, so I will not change camber settings again until I run the car and see what I have.

Here's the thing, anything in excess of -.5 degrees will drastically reduce tire life and since you can't corner at 1 g around the neighborhood, you will be ruining good tires for really no reason. I would set up your street car with a -.5 on the front and about .25 on the rear. Then move tires side to side every 4-5000 miles. Ya take them off the rim and run them inside to outside but in the same direction.
 

Terry Oxandale

Skinny Man
Here's the thing, anything in excess of -.5 degrees will drastically reduce tire life and since you can't corner at 1 g around the neighborhood, you will be ruining good tires for really no reason. I would set up your street car with a -.5 on the front and about .25 on the rear. Then move tires side to side every 4-5000 miles. Ya take them off the rim and run them inside to outside but in the same direction.
I would have fully agreed with you on this aspect, but a recent daily driver that I purchased (which is a blast to drive, and better than a cup of coffee in the morning) is my FRS. I've run -2.5 front, -2.0 rear for over a year now, and tire wear is perfect. Fast perhaps (Michelin Pilot Sport PS2), but perfectly even across the tread, BUT, they are only 245 widths, so that does allow more flexibility that wider tires. Toe is critical though!
 
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Joel K

Supporter
With the new tires on the rims I think the 255/30/19 will work. Ideally 265/30/19 would be best, but the only two Michelin Super Sport Runflats were the 285/30/19 or the 255.

The shop I went to today was great, sorry I did not go to them first but it is what it is and move on.

Here are some pics of the 255s. Interesting how the 285 looked pinched on the rims with the tire overhanging the rim while the 255 looks slightly pulled off the rims.

Pic with zero camber...
2C25B780-38E4-4718-B945-7218C841E086.jpeg


Pics with 1.5 degree camber..
23F5EAF9-C8C0-436A-AEB5-B6038E151C98.jpeg


A60A4C1A-5286-4B44-B742-6090553BA034.jpeg


This is how the 255 sits in the wheel well with 4.25” Ride height. Both front wheels need to be moved back a bit but looks pretty good with equal distance around the tires.....
358C7F81-6BAA-4A44-99B6-5A426DB693E3.jpeg


Moral of the story, the 285/30/R19 tires are not a good choice with 9.5” rims unless you don’t mind the tire poke or want to add fender spats or widen the front fenders a bit.
 
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Agreed. On my car - the inside tire in a turn into a shallow driveway caught the trimmed lip of the fender and broke a big chunk of the fiberglass off the outside of the wheel opening.. Not good. I recommend cutting the inner return lip back to about 1/8 inch and then filling the inner side of the fender/lip with fiberglass chop. This eliminates any sharp lip that can catch on a rotating tire.

You can thank me when you never have to repaint a front clip.
 
I recommend cutting the inner return lip back to about 1/8 inch and then filling the inner side of the fender/lip with fiberglass chop.
That's about right. I trimmed mine to about 1/16" from say 10 O'Clock to 2 O'Clock then smoothed the top edge in. I was tired of tire smoke so probably got a bit carried away! I have fender vents and have had to trim the fastening hardware down to 1/8" to stop the tires from rubbing on those as well.
 

Ken Roberts

Supporter
I would definitely compare the back offset with someone else's wheels in the same size. Personally I think you have been given the wrong offset wheels in the front. The only other car I have seen with poke out that bad is the twin turbo'd car. He had to put spacers behind the front wheels to clear the huge Brembo 6 piston calipers.
 
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Joel K

Supporter
I would definitely compare the back offset with someone else's wheels in the same size. Personally I think you have been given the wrong offset wheels in the front. The only other car I have seen with poke out that bad is the twin turbo'd car. He had to put spacers behind the front wheels to clear the huge Brembo 6 piston calipers.
RCR confirmed I have the right wheels/offset so I mentioned that they should update the 19” tire recomendations on the web site.
 
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