Tire size info needed.

[smithbrother]

I am building a 1/4 scale model of the Infiniti prototype race car that was at Pebble Beach a month ago.

 

From pictures of the tires, the rear shows the size as  8.60 - 18.

 

What would  be the overall diameter of this tire, tire tread width, and cross section?

 

Once I know the diameter, I will divide by 4 to come up with my model tire diameter. 

 

Thank You,

 

Dale in Indy

[Guest]

8.6+8.6+18x3.14

[smithbrother]

8.6+8.6+18= 35.2"

 

I can believe the 35.2" tire diameter, if the 8.60 is the distance in inches from the rim edge to tread surface.  Then the circumference would be 110-1 /2".

 

I'm thinking the 8.60 is the tire cross section width , and NOT the actual rubber height outside the rim but I can be wrong ?

 

I know for fact the rim is 18".

 

Comments are most welcome.

 

Thank You,

 

Dale in Indy

[JACK M]

I had to do some figuring like this recently.

I did a google search and found a chart that gave all dimensions for given sizes.

Don't recall the site right off hand but maybe 'Tire Rack' or the likes.

It stared with wheel size, so there was a list for tires dims for all tires that had 14 inch wheels for instance.

I was searching for tires for some 18 inch dia wheels and found what I needed.

[JACK M]

This might be it,

Note the small tabs at the top, wheel dia.

 

https://tiresize.com/chart/

Edited October 15, 2017 by JACK M (see edit history)

[smithbrother]

Thanks, the tires in question are  marked as 8.60 18, and no other number/numbers listed.  The chart you provided, and the ones I found ask for more numbers. 

 

I sent a note to TIRE RACK, but they won't respond for two days, so thought someone on this site might have good info.

 

Thank You,

 

Dale in Indy

[Marty Roth]

6 hours ago, Tinindian said:

8.6+8.6+18x3.14

That would work for a 8.6x18 as the type used on early brass & nickel cars, but-

in this case I believe that the 8.60 refers to the section width, and NOT the height of the tire sidewall above and below the rim.

Typically that measurement could be 80, 85, or even 90%, and possibly 100% of the section width so that measurement would be somewhat off.

 

Your overall correct tire diameter would have been 40.70 inches

 

Hope this helps...

 

I gleaned this information from the COKER site and relates directly to your size - even though it states 7.50-18, 

the actual section width is 8.60:

https://www.cokertire.com/tires/styles/military-and-truck/deka-750-18-truck-tire.html

 

• Brand: Deka
• SKU: 587102
• Product Size: 750-18
• Rim Diameter: 18
• Tread Width: 8.50
• Section Width (Actual): 8.70
• Overall Diameter: 40.70
• Max Load Capacity: 2540@65PSI
• Recommended Rim Width: 6.00 - 6.50
• Tube Type or Tubeless: Tube Type

[smithbrother]

Thank You,

 

The car I am making as my 11th. Large model, it's the 1940 Infiniti race car updated to what Infiniti designers felt it would look like if built today.

 

My model, is a 1/4th scale, approx. 36" long piece.  

 

It was a winner at Pebble Beach a month ago,  

 

GOOGLE, (images of INFINITI prototype race car), to see what I'm building.     You will see the tires appear tall, and skinny.  I blew up one of the pictures and read the tire markings.  Marty, you are right it's a older piece, not brass, but old.

 

I'm heavy into the body shape, like my other models this will be a 1500-2000 hour build.  This is my most trying piece, but I love doing those tasks I don't know how to do.  For what it's worth, I love model building, the thought process is huge, but fun, FUN IS GOOD.

 

Dale in Indy,

 

BEN, no chance it will have a VISOR.  Sorry my friend.

 

'

[g-g-g0]

Just Googled it! That thing is really cool! Dale you do some amazing work!

[Bloo]

Those tires are Excelsior Comp H, from the pictures I found posted on the web.

 

Where did you find 8.60-18? That size is not currently available in Excelsior Comp H, and I can find no clue that it ever was.

 

For 1940, I would normally expect an aspect ratio of about 90, ((8.60 x 2 x 0.9) + 18 = diameter) but the data for those tires works out to about 100%, and also they seem to have the section width a little skinnier than expected!

 

8.6 + 8.6 + 18 is probably right, and less than 8.6 wide.

 

Data for the Excelsior Comp H is here. You can work out some of the other sizes to see the trend and make a good guess, multiply inches by 25.4 to get millimeters.

 

http://www.longstonetyres.co.uk/page/excelsior-comp-h

Edited October 16, 2017 by Bloo (see edit history)

[smithbrother]

Bloo, I have close up photos of the car while it was shown at Pebble Beach late August.

 

I zoom in on the rear tire and it is the exact tread pattern that Excelsior Comp H offers.

 

The tire on the prototype is clearly marked 8.60 18.

 

Infiniti may have had Excelsior make these special for the prototype.  I will try to contact Excelsior to learn more.

 

Thank You,

 

Dale in Indy