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PostPosted: Thu Nov 30, 2017 6:12 pm 
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I think it might be helpful to hear what some different tire and wheel combos are producing as our new NASA Tire Section Width.

If you share the details on your widths I will update this post to consolidate and create a database. I understand it won't be perfect and it will be on the honor system, so consider that before dropping a bunch of coin.

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

???.?mm - 225/45/17 - Bridgestone - RE71R - 32psi - 2015 - 17x7.5 - BMW - OEM - digital calipers - 30mm deep

From 6.1.2 of the 2018 Rules - https://nasa-assets.s3.amazonaws.com/do ... -29-17.pdf

“NASA Section Width”

DOT tire width is determined by a measurement of the “NASA Section Width” of the largest tire (if staggered sizes) on the vehicle in post-competition impound/inspection, without changes to tire inflation (may be allowed to cool to pre-competition pressure). The tire may be measured while off or on the vehicle at any location not affected by ground contact sidewall deflection. A tire's NASA Section Width is the measurement of the tire's width from its inner sidewall to its outer sidewall using the NASA Section Width tire measurement tool(s) (excluding any protective ribs, decorations or raised letters) at the point 30mm deep to the tread surface on a new tire for vehicles 2400 lbs. or greater, and 23mm deep to the tread surface for vehicles less than 2400 lbs.

I will update this post with new measurements as they come in. If there is a measurement already listed similar to yours please contribute your measurements as well. There will likely be some variances like worn shoulders or wheels that don’t run “true” to size...so the more data points the better.

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

Image


Last edited by MemphisRob on Mon Dec 11, 2017 4:29 pm, edited 4 times in total.

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PostPosted: Thu Nov 30, 2017 7:09 pm 
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This is great idea. Will edit as soon as I figure out how tf to do it.


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PostPosted: Fri Dec 08, 2017 7:44 am 
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So, I ordered a Neiko 12” digital caliper from Amazon and checked some tires in the garage. I did this really quickly and didn’t check psi...but I figured I could update later.

One compromise I made was using my stud finder as a “spacer” to reduce the caliper “tongs” measurement to about 3cm. I’m considering cutting the “tongs” to exactly 3cm to be more exact with the measurement.

Anyway, here are some preliminary findings and measurements. I wil round up on millimeters.

Both the 225/45/17 and 235/40/17 Maxxis RC1 on an identical Borbet 17x8” Wheel are just about the same 229mm wide.

235/40/17 Maxxis RC1
unmounted it is 241mm wide at 3cm
17x8.5” D-Force LTW Wheel is about 234mm wide at 3cm
17x8" Borbet it is 229mm wide at 3cm

17x8" Borbet rim it comes in right at or maybe under the 226mm threshold at 23mm (could be a cheater tire for the sub 2400lb cars?)... might be fine as is on 8" wide but it is close for sure... on a 7.5" wide rim I am just about sure it will be well under the 226mm.

225/45/17 Bridgestone RE71
Unmounted this is over 226mm at 3cm, but under 226mm at 23mm.
17x7.5” OEM BMW Wheel is about 221mm


Honestly, it looks like tires with a much more “squared” shoulder will have a nice advantage in the way these are measured 3cm down the sidewall. Rounded shoulders give up quite a bit of contact patch on each side. Also, it looks like the wheel width will be a significant variable on how wide or narrow a tire will run. I measured the 225 RE71 on a 7.5” wide tire at 211mm at 30mm deep but at 23mm deep it would be even narrower...so well within the 226mm Section Width limit for sub 2400lb cars.

https://www.dropbox.com/sh/7b0pzrq0l51p ... ulLta?dl=0


Last edited by MemphisRob on Sun Dec 10, 2017 11:08 am, edited 3 times in total.

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PostPosted: Sat Dec 09, 2017 3:54 am 
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Measured NASA Section Width - less than 266mm (probably 5 mm to spare easily)
Tire Size - 245/40/18
Tire Brand - Hoosier A7
Tire Pressure / Date Code - 26 cold/1417
Wheel Size - 9.5" rim
Wheel Brand/Wheel Model - APEX ARC 8
Method of Measurement - 266 x 30 mm NASA Template

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PostPosted: Sat Dec 09, 2017 5:58 am 
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Clavette wrote:
Measured NASA Section Width - less than 266mm (probably 5 mm to spare easily)
Tire Size - 245/40/18
Tire Brand - Hoosier A7
Tire Pressure / Date Code - 26 cold/1417
Wheel Size - 9.5" rim
Wheel Brand/Wheel Model - APEX ARC 8
Method of Measurement - 266 x 30 mm NASA Template


Thanks Clavette.

I was wondering if the Hoosier 245’s would still be under 266mm on a larger than 9” rim.

Since 9.5” wide rims still aren’t at the limit, I hope someone measures a 245 on 10” rim.


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PostPosted: Sat Dec 09, 2017 2:09 pm 
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MemphisRob wrote:
Clavette wrote:
Measured NASA Section Width - less than 266mm (probably 5 mm to spare easily)
Tire Size - 245/40/18
Tire Brand - Hoosier A7
Tire Pressure / Date Code - 26 cold/1417
Wheel Size - 9.5" rim
Wheel Brand/Wheel Model - APEX ARC 8
Method of Measurement - 266 x 30 mm NASA Template


Thanks Clavette.

I was wondering if the Hoosier 245’s would still be under 266mm on a larger than 9” rim.

Since 9.5” wide rims still aren’t at the limit, I hope someone measures a 245 on 10” rim.


Someone measured the 245/40/18 on a ten inch with a cardboard template. You can find the pictures in the NasaMa TT Facebook group. Fits questionably, also its not a arc8


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PostPosted: Sat Dec 09, 2017 8:46 pm 
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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


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PostPosted: Sun Dec 10, 2017 6:04 am 
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Hoosier R7 225/40/17 on 9.5" rims makes the 257MM template with room to spare.

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PostPosted: Mon Dec 25, 2017 9:10 pm 
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Merry Christmas to all!!

Anyone do some tire measuring in the last couple weeks? Or is there another forum or Facebook group that has posted any more widths or other sizes?

Any contributions are appreciated.

Thanks.


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PostPosted: Wed Dec 27, 2017 12:13 pm 
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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!


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