Hoosier A7 and A6 sizes not necessarily identical Options

[mskala]

Foolishly I've been thinking that for A7, they just changed the compound
and removed more 'tread' lines. But I recently found some other board's posts
where they are definitely wider than A6. The only size I can use is 205/45/16
and Hoosier's chart actually shows a narrower section for the A7 version.

So, since I have no more room in the back, I have a couple on order so I can
mount one and measure. I don't need them yet but figure if I find out early there
may still be 4 A6's somewhere, or I'll need to change brands (IMG:style_emoticons/default/sad.gif)

Will report back in a week or so.

[mskala]

From lotus guys:

[john914somers]

So are the 17" tires going to be for sale???

[mskala]

So are the 17" tires going to be for sale???

sorry for confusion, those aren't mine. I have a narrow body so will be
measuring 205/45/16 against the A6 mounted.

[brant]

Mark,

those kinda look like they are unmounted 7's?

the hoosier specs indicate the 7's are actually narrower than the 6's were in the same sized....

your internet pic doesn't support that though..

now I'm on the fence between the 205/225 I'd really love to hear what your actual measurements are when you do your trial fitment

thanks
brant

[naro914]

Damn...I hope they aren't THAT different.
I have an old set of 245/45 16 R6 on Huey for the Hawk. I ordered a set of R7 for when we get there to have them mounted.

every spec I read says R6/R7 are basically the same size...are you SURE that tire on the right in the picture is a 245 and not a 225? I can't believe they would be that much different

[mskala]

So far I only have the info I showed. Points taken, it is possible these guys are
wrong or doing something dumb like comparing mounted to unmounted.

If you want something done right, you have to do it yourself (IMG:style_emoticons/default/biggrin.gif)

For the old kumho and old A6, the listed measurements have been pretty good.
I'm hoping that in my size the section width is a bit narrower as they are listing for
A7.

[Han Solo]

If anyone is interested, I can do some preliminary results on A7s.

Background, I've got a lot of experience on A6s mid-engine Porsche (mostly Cayman & Boxster). Last year I finished the season on A6 on 914/4 in D Prepared SCCA Solo class. This year I've got 27 runs so far on 275/35/15 rear and 245/40/15 fronts with A7 Hoosier. I'm also running Duralite aluminum wheels which are super light. Max. camber front and back without camber plates. OEM front sway bar and no rear sway.

So far I'm liking the A7. Last year I ran a square set-up with the 275 width stuffed on to the 8" front wheels. This season I'm not missing the loss of about 2" of contact patch on the fronts. No increased under-steer. I can report that it does take twice as long to get the A7s up to running temps. Last weekend we were running a 50 sec. course with about 12 min. between runs and air temps in the mid 90's. The rears finally came up to 125-135 degrees after the third run on asphalt. Grip increased fairly evenly with the increased tread temps. I have heard reports that A7s are not a good wet (as in no standing water, puddles) tire. Also, it appears these are going to last much longer than the A6s ever did. After 27 runs it looks like I won't have to flip the tires till about 50 runs (for even wear). This is good news as the most I ever got out of the A6 was 80 runs (with one flip) and those last 20-30 runs weren't competitive. Reports indicated the A7 may good good up to 100 runs. Wouldn't that be nice (IMG:style_emoticons/default/biggrin.gif)

[brant]

If anyone is interested, I can do some preliminary results on A7s.

Background, I've got a lot of experience on A6s mid-engine Porsche (mostly Cayman & Boxster). Last year I finished the season on A6 on 914/4 in D Prepared SCCA Solo class. This year I've got 27 runs so far on 275/35/15 rear and 245/40/15 fronts with A7 Hoosier. I'm also running Duralite aluminum wheels which are super light. Max. camber front and back without camber plates. OEM front sway bar and no rear sway.

So far I'm liking the A7. Last year I ran a square set-up with the 275 width stuffed on to the 8" front wheels. This season I'm not missing the loss of about 2" of contact patch on the fronts. No increased under-steer. I can report that it does take twice as long to get the A7s up to running temps. Last weekend we were running a 50 sec. course with about 12 min. between runs and air temps in the mid 90's. The rears finally came up to 125-135 degrees after the third run on asphalt. Grip increased fairly evenly with the increased tread temps. I have heard reports that A7s are not a good wet (as in no standing water, puddles) tire. Also, it appears these are going to last much longer than the A6s ever did. After 27 runs it looks like I won't have to flip the tires till about 50 runs (for even wear). This is good news as the most I ever got out of the A6 was 80 runs (with one flip) and those last 20-30 runs weren't competitive. Reports indicated the A7 may good good up to 100 runs. Wouldn't that be nice (IMG:style_emoticons/default/biggrin.gif)

Any thoughts on width between the two ?

[Han Solo]

Any thoughts on width between the two ?

I didn't do a side by side comparison as shown in the earlier post. However, I've got the same clearance on the rear flares (very close) with the A7 as the A6 did. The fronts are different of course going to the 245 from 275. To me, the shoulders appear to have the same contour (although I remember some sizes of A6 offered with square shoulder). I did notice that the wear "dimples" are much deeper on the A7. I didn't measure them but I suspect the dimples are deeper than the new dashed tread pattern. Perhaps there's more compound material before you get to cord. Again, being very optimistic here (IMG:style_emoticons/default/rolleyes.gif)

[mskala]

Okay, finally received the A7 and test mounted. Verdict, at least in this size,
is they are identical. Same section width as my A6. Same rounded shoulder.
(IMG:style_emoticons/default/piratenanner.gif) So, I won't be looking for alternates for a while.

[naro914]

Agreed. R7 on the car now, R6 came off. Same size.

[brant]

Update from one of the Hoosier engineer reps
I was continuing to hear that some tires were the same other tires were not
and on here and pelican it was reported that new molds were created for some diameter of tires and that there were large size differences in certain diameters, no sizing differences in other diameters

so here is the reply I got specific to 225/45/15 A7

-------------------------

Brant,

Thanks for writing and good question. Concerning dimensional differences between the “6” and “7” series DOT track tires, there were slight changes to the Tire Widths from P245 – P225 – P205 and P185. However, if you use a tire size that is on the wider scale – P255, P265, P275, P315 and wider, the dimensions did not change.

The most noted tire size difference was the P245/40ZR-17 A7 and R7. I have not had anyone say they had issues with your tire size – P225/45ZR-15 A7 / R7.

I have listed the current A7 / R7 dimensions alongside the previous R6 / A6 dimensions. I don’t think you will have any rubbing issues, but do have the P205/50ZR-15 available if you do.

P225/45ZR-15 R7 / A7: Diameter – 22.8” x Tread Width – 8.6” x Section Width – 9.3” – Design Rim – 7.5”

P22/45ZR-15 R6 / A6: Diameter – 22.9” x Tread Width – 9.0” x Section Width – 9.8” x Design Rim - 7.5”

Looking at both dimensions, it actually looks like the R7 / A7 is a bit narrower, so you will be fine.

I would go ahead and order the A7 for your car.
Anything else you need, please write me.
Thanks for using Hoosier Tires.
Jeffrey A. Speer
Sports Car Product Manager