Pizza Cutters?

[255/85]

Toyo and BF Goodrich have 34x10.50R17 options. Both are all-terrains though.

 

[Tinerfeño]

Yes, the calculated diameter based on the metric sizing is 1/2" less than the manufacturer's specified diameter.

Based on what?

Metric sizes are pretty accurate on dimensions just allowing some tolerances. For example the width of a tyre is measured on one specified wheel width, with a narrower wheel the width (measered from tyre sidewalls) will be less and with a wider wheel more.

The diameter is not straightly visible in the nomination. It is calculated by 2 x nominal width x profile + wheel diameter. In this cese:
2 x 255 mm x 0,85 + 17" x 25,4 mm/" = 865 mm, which is 34,1".

 

[snowball]

Spec's from Mickey Thompsons website

 

[Tinerfeño]

Seems to show double dimensioning: 255/85R17 and 35x10.00R17 and most probably has been manufactured to later of these.
Does the tire has also double markings on sidewall?

 

[TCMColorado]

Based on what?

Metric sizes are pretty accurate on dimensions just allowing some tolerances. For example the width of a tyre is measured on one specified wheel width, with a narrower wheel the width (measered from tyre sidewalls) will be less and with a wider wheel more.

The diameter is not straightly visible in the nomination. It is calculated by 2 x nominal width x profile + wheel diameter. In this cese:
2 x 255 mm x 0,85 + 17" x 25,4 mm/" = 865 mm, which is 34,1".

Per the specs from Mickey Thompson the actual inflated diameter when unloaded is 34.6”. The calculated diameter based on the metric size is indeed 34.1”. That is a difference of .5” or 12.5mm. That variance is more than a “tolerance” .

 

[TCMColorado]

Toyo and BF Goodrich have 34x10.50R17 options. Both are all-terrains though.

The BFG in this size is comically under sized. I have measured the actual diameter at 33”. This was at a pressure of 30 psi with the wheel/tire horizontal on the ground with no load and measured at the center of the tread face.

 

[Revelstoke]

I wasted little time swapping out the OE KO2's for Toyo Open Country III's in a 255/80R17...had no issue selling the BFG's which made it all a little financially easier. Appreciate the additional 1/2 inch or so of ground clearance. Have had both types, although differing sizes, over the past few years on other vehicles and found the Open Country's offered better snow performance overall for at least the first season or so which is a priority in my neck of the woods. On a side note; the Toyo's balanced out tremendously better requiring a quarter of the wheel weights than were with the BFG's!

 

[255/85]

The BFG in this size is comically under sized. I have measured the actual diameter at 33”. This was at a pressure of 30 psi with the wheel/tire horizontal on the ground with no load and measured at the center of the tread face.

I wasted little time swapping out the OE KO2's for Toyo Open Country III's in a 255/80R17...had no issue selling the BFG's which made it all a little financially easier. Appreciate the additional 1/2 inch or so of ground clearance. Have had both types, although differing sizes, over the past few years on other vehicles and found the Open Country's offered better snow performance overall for at least the first season or so which is a priority in my neck of the woods. On a side note; the Toyo's balanced out tremendously better requiring a quarter of the wheel weights that were with the BFG's!

33" is about right for our vehicle. I'll stick with the Toyos when we upgrade since snow performance is paramount for us. The 34"Goodrich's are spendy considering they come up short anyway. Thanks guys.

 

[TCMColorado]

To bring a data point to the Mickey Thompson discussion I precisely measured the circumference of my spare tire at 40 psi in the middle of the tread face. This was 108.75". Which equates to a diameter of 34.62". So the measured diameter matches the Mickey Thompson specification of 34.6" and is .5" greater than the converted metric size of 255/85R17. The tread face measures 8.69" at its widest point, this does not included the sidewall lugs. It is very much a skinny 35" tire.

 

[Commodore]

33" is about right for our vehicle. I'll stick with the Toyos when we upgrade since snow performance is paramount for us. The 34"Goodrich's are spendy considering they come up short anyway. Thanks guys.

I guess it depends on how you want to use your truck.

 

[TCMColorado]

To bring a data point to the Mickey Thompson discussion I precisely measured the circumference of my spare tire at 40 psi in the middle of the tread face. This was 108.75". Which equates to a diameter of 34.62". So the measured diameter matches the Mickey Thompson specification of 34.6" and is .5" greater than the converted metric size of 255/85R17. The tread face measures 8.69" at its widest point, this does not included the sidewall lugs. It is very much a skinny 35" tire.

I am updating the measured size of my Mickey Thompson tires mounted on the OEM steel wheels. I suspected there was an error in my original measurement because I did not have a long enough flat tape and resorted to using a standard carpenter tape which would not lay completely flat against the tire. To correct this I bought a completely flat tape reel which does conform perfectly to the circumference of the tire and has zero flex. Using this tape the measured circumference is 109.875" (average of three measurements) at the center of the tread face fully unloaded while on the back of the vehicle at 40 psi. This equates to a diameter of 34.97" which is .37" greater than the specified diameter and .9" greater than the converted metric size. These tires are tall, a true 35", and because of the narrow width they do not rub under any conditions on the OEM suspension.