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PostPosted: Thu Dec 28, 2017 4:42 pm 
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bimmerman325i wrote:
MemphisRob wrote:
Looks like the NASA MA folks have been busy checking tires... Thank you very much to the people that contributed.

Anyway..these are from the Facebook page.. I figured I'd add them here.

225/45/17 R7 on 17x8 Image

225/45/17 R7 on 17x10 Image

245/40/17 A7 on 17x10 Image

245/40/18 A7 on 17x10 Image

255/40/17 RC1 on 17x10 Image


The pictures don't seem to work. Can you please re-share or re-link them? Or, say which passed and which didn't? Thanks!


I can't see them on my iPhone but I can see them on my laptop... maybe I need to upload them to something other than dropbox.

Can you see this image?

https://www.dropbox.com/s/l4oa9bjm4qvnfbn/Photo%20Dec%2011%2C%206%2012%2038%20PM.png?dl=0

https://www.dropbox.com/s/l4oa9bjm4qvnf ... M.png?dl=0


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PostPosted: Fri Dec 29, 2017 12:28 pm 
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MemphisRob wrote:

I can't see them on my iPhone but I can see them on my laptop... maybe I need to upload them to something other than dropbox.

Can you see this image?

https://www.dropbox.com/s/l4oa9bjm4qvnfbn/Photo%20Dec%2011%2C%206%2012%2038%20PM.png?dl=0

https://www.dropbox.com/s/l4oa9bjm4qvnf ... M.png?dl=0


That works, thanks!

Bummer that the 245/40/17 Hoosiers are over the 266mm template on a 17x10. Darn.


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PostPosted: Fri Dec 29, 2017 4:38 pm 
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Thanks for making a spreadsheet.

Interesting that a 245/40/17 A7 fits the 266 on a 10" but the same size R7 does not.

My theory is that the apex rims run wider than most.

Here is a 18X10 I have sitting


ImageUntitled by patrick cornwall, on Flickr
ImageUntitled by patrick cornwall, on Flickr



Here is a 225/40/17 R7 on a apex arc8 17-9.5

Just fits in the 257 template

ImageUntitled by patrick cornwall, on Flickr

Thats all I can contribute for now. If anybody has a 255/35/18 on a 10" arc8, I would love to know if they fit in the 282 template. Greg seems to think it won't fit. That would be unfortunate because its the ideal size for the e36, being that its not nearly as tall as the 275/35/18


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PostPosted: Thu Jan 18, 2018 6:12 pm 
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Measured NASA Section Width - Tire Size - Tire Brand - Tire Model - psi - Date Code/Age - Wheel Size - Wheel Brand - Wheel Model - Method of Measurement - 23mm/30mm deep

NO GO on the 266mm/30mm (by about 1-2mm)!
Hoosier R7, 245/40x17, 30 & 35 psi, APEX ARC-8 17 x 9.5" wheel

I definitely wonder as above if this wheel is just bigger than other 9.5's?
Going to get a 9" and retest, but suspect it might fit--just needed a little narrower....
I have these tires on other 9" wheels and other 8.5's, and they are compliant by 2-5mm.

So, the new system will not only catch tires that are not as advertised, but wheels that are larger than listed as well....definitely evening out the playing field for all.

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Greg Greenbaum
National TT, PT, & ST Director
Nat. Medical Director
greg@nasa-tt.com


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PostPosted: Fri Jan 19, 2018 7:48 am 
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We did a measurement on our ST3/E0 E36 18x10 Apex ARC 8 & EC-7 wheels and 255/35/18 Hoosier R7. It did not appear to fit the 282mm template, but just barely missed, by maybe 1mm, that is a pretty tight tolerance. Is 1mm of section width really that much of an advantage?

I know going back into the PT classing history journals, the 255 has always been the "cheater size". But this is ST...not PT? The primary reason for using this size for us was actually the height of the tire. Similar tread width (if not the same) between the 275/18 and 255/18, the 255/18 has a little more rounded shoulder than the 275/18 I believe (I don't honestly know which is better? square vs. rounded?). The 275/18 tire, however, is much taller (25.5" vs. 24.8"), which means you have to raise your ride height and now your cg.

Luckily for people who run 17" wheels, as in the 275/17s (which qualifies for a .3 modifier), they offer a lower profile 275/35 which maintains a tire height of 24.7". But for 18s, the 275 tire size just sucks for the E36. Maybe we lobby Hoosier to relabel the 255 to a 275... :lol: :lol:

(Full disclosure, in my sprint/TT car, I run 285/18s, so this new rules doesn't change much there)


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PostPosted: Thu Jan 25, 2018 12:21 am 
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I don’t really see how the 275/17 is going to work, with a listed section width that’s even larger than the 255/18. 11” vs 10.8”

This is a real headache trying to find a tire wider than the 245 on a 9” rim to run on a e36 (for tt contingency). Yes there are wider options, but they are all really tall. Meaning, really hard to fit and huge gearing reduction.

Any chance of ammending the 282mm to say 286 or something?


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PostPosted: Thu Jan 25, 2018 1:22 am 
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Pat533i wrote:
I don’t really see how the 275/17 is going to work, with a listed section width that’s even larger than the 255/18. 11” vs 10.8”

This is a real headache trying to find a tire wider than the 245 on a 9” rim to run on a e36 (for tt contingency). Yes there are wider options, but they are all really tall. Meaning, really hard to fit and huge gearing reduction.

Any chance of ammending the 282mm to say 286 or something?

Our testing of the 275/17 and 18 Hoosier on a 10" wheel had no problem fitting the 282mm tool.

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Greg Greenbaum
National TT, PT, & ST Director
Nat. Medical Director
greg@nasa-tt.com


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PostPosted: Thu Jan 25, 2018 10:07 am 
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Has anyone measured 245/40/15 Hoosier on a 10" wheel with the 266mm template? I am suspecting that it will be very close as it runs narrower than both the 245/40/17 and 245/40/18 Hoosiers with the 17" being the largest. The 18" Hoosier seems to have cleared on 9.5" Arc wheels which might run large for the given size so could almost be 10" wheels.


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PostPosted: Thu Jan 25, 2018 4:14 pm 
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Greg G. wrote:
Our testing of the 275/17 and 18 Hoosier on a 10" wheel had no problem fitting the 282mm tool.



Good to hear. I hope it was measured on a apex wheel haha


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PostPosted: Thu Jan 25, 2018 10:26 pm 
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Pat533i wrote:
Greg G. wrote:
Our testing of the 275/17 and 18 Hoosier on a 10" wheel had no problem fitting the 282mm tool.



Good to hear. I hope it was measured on a apex wheel haha

Unfortunately not.
I'm going to test out the 9" Arc-8 with the 245/40 x17 R7 in the next few days. I've got my fingers crossed--should be okay--just missed on the 9.5" by 1-2mm.

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National TT, PT, & ST Director
Nat. Medical Director
greg@nasa-tt.com


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