Hoosier A7 or R7 on a C7 Z06?
 

Anyone here running these? These are DOT racing slicks (they have two "cosmetic" grooves", although there is/was some company that would cut treads into them), A7 for autocross, R7 for circuit racing. The rears are a match at 335/25/20, but the closest fronts are 295/30/19 (about 1% larger diameter, may cause the C7 to think the rears are slipping a bit). I've seen a few cars with these at some local car shows.

A7's are also really great for time trials. They give you amazing grip for a handful of laps. They'll cycle out pretty quick tho..

Be mindful that the Hoosier sizes are generally larger than normal sizes IE the section widith on a 335/25/20 A/R7 is 14.2 vs 13.5 on the pilot super sport.
Also the diameter is 27.1 hoosier vs 26.6 pss

The C7 isn't to limiting when it comes to weird size tires once you're in PTM or TC/AH off. fwiw. You can pretty much cram whatever fits on your car.

don't shop for tires based on "size" without actually looking at tire specs. you'll have a bad time.

ETA: Hoosier tire sizes
If I was gonna buy tires for the stupid OEM wheel size for a Z06 or GS I would get

Hoosier R7 305/30/20 - 27.1 13.2 vs 26.6 13.5 (PSS)

Hoosier R7 295/30/19 - 26.1 11.5 vs 25.8 11.3 (PSS)

I missed an edit. Fronts are 26.1 versus 25.8. So fronts ~+1%, rears ~+2%. I assume this isn't enough to trigger an engine braking causing the rears to slip warning, but it could interfere with the assists, or at least TC, not sure about the stability control. Is a camber change needed with these tires, or is that just an issue with the bias ply racing slicks used on the smaller cars (Caterham, Formula Ford, ... )?

For any slick or semi-slick I would recommend as much camber as you can get out of your car.

Not sure if you're planning on street driving on these tires but if you do you will be making a very expensive mistake.

A7s for all!

I was asking for one of the guys at a local weekly car show, who has a 2016 C7 Z06 A8 Z07. I don't plan on tracking my car (2015 C7 Z06 M7 3LZ (without Z07)) at either a drag strip or road course, so I will only be using the Super Sport tires. One of the other guys that used to go to the car show tracked a Caterham, using the R7's with the softer compound on 13" rims, pulling lateral 1.5g, which is good for a non-downforce car, which is why I remembered the A7 / R7 tires, and asked here about them before I mention them to that guy at the car show. Thanks for the replies.

I run either the A7 or R7 in 18 inch diameter sizes. Front 315/30/18 on 18x11 wheels and Rear 345/35/18 on 18x13 wheels. That combo works very well. Diameters are close to stock and a limited number of tires are available as scuffs Vs new so you can save some money on tire purchases.

Bill

If I understand it correctly, I think you should focus on tread width, not sectional width. The tread width will be measured as mounted on a rim. If the measured rim (listed in the spec) is different size than what you're using, you can also add/substract 0.2" for every 0.5" wheel size increment/decrement to reach your specific wheel size as an approximation.

PSS ZP actually runs incredibly wide. Some of the sizes (like the TPC spec Corvette sizes) actually run wider than the corresponding Hoosier tires. I realized this when I put my Miata tires (R7 285/30/18) next to PSS ZP 285/30/19; PSS ZP was wider.

https://lh3.googleusercontent.com/Q7...=w1228-h922-no
The tire at the bottom left is 285/30/19 PSS ZP. The tire at the right is Hoosier R7 285/30/18. Per manufacturers' specs, PSS ZP has 11.3" tread width, while R7 has 10.6" tread width, which clearly shows in the pic (they are both not mounted).

If you compared sectional widths, however, you'd see 11.5" vs. 11.4", and think that they're about same width. Sectional width is very much dependent on radial belt design, and doesn't even change much with different wheel widths. As such, it might not be as helpful : )

for autocross i would like to use these hoosier A7 sizes on my 2016 C7 Z07:

P315/30/ZR19
P335/25/ZR20

The rears are the exact size of the stock tires, so I assume that is the best tire.
The front A7s are the ones I am worried about. They are 30mm too wide. Would this even fit? If so I assume this would be the best performing combo for the c7 z06 right?

As Jed Clampert would say..."My brain hurts from all this ciphering"! I want the best tire for the track while retaining my current wheels on my '17 Z07-7 CCB.(I have two sets) Seems Hoosier or Toyo is my choice? I hate the Cup2's as they wear out to quickly, with no big grip benefit over the pilot SS(which I really like). So, is there anybody actually running these off sizes that are available? obviously not? Why? Probably because we 07 CCB guys are caught in a whirlpool, while the other racer guys have zeroed in on the choices available with Steel brakes and differing wheel sizes? Seems at competitionmotorsports.com they have the 335/25/20 R888RN listed and the N denotes a narrower tire than usual? What Da? No actual details on their site, w full specs? Would it make any sense to run R7 on front with A7 on rear? Why not? I would also think that a Hoosier A7 rear would also be best for drag strip action, as the work better/quicker on cooler temps? and the A7 should never get greasy hot on a road course, as my car will run hot/limp before the that happens. Three hard laps is all I'll get running 9/10ths.

What ya'll think?

Subbed

Call Competition Motorsport and ask their advice. They’re great guys and they’re racers who know their stuff. They won’t lead you wrong.

Given new tires the Hoosier will perform better than the Toyos.

Bill

Just ordered my set of R7 from competitionmotorsport.com. They were even $200 cheaper than tirerack.com.
Now, how about some skinnies for the front that will clear my CCB's for drag racing? any recommendations? I'm thinking my R7 Hossier rears will launch well, after a decent burnout?

Try trackdaytire.com with a coupon code (like msrvip).

I believe you are incorrect
 

According to the Hoosier website the section width is 13.2 on the 335 not 14.2 which makes it a no problem over the OEM Michelin SW of 13.5. So I'd go with the 335 instead of the 305. I think your characterization of the 20" wheel is "stupid OEM" is also a bit off. If you want an OEM drag ready car from the factory, buy a demon or similar.

I don't think "drag racing" was what he had in mind when he dissed 20". Sure, higher diameter tire with the same tread width will have a larger contact patch (since the rate of curvature is slower, making the tire surface flatter and touching longer to the ground; not sure what the term is for that). That said, when you get to 20", the tire and wheel weights are substantially higher, and there are also less choices. Moreover, Corvettes have always had limited clearance in fenders, so taller tire will also limit you to a narrower width.

I've personally settled with 18x11, 19x13 wheels, and I use 315/30/18 front, 345/30/19 rear R7s for track use. I should note, if I could, I'd rather do 335/30/18 front, but I don't think there's enough clearance up front. These cars seem to perform better as you go larger and larger up front.