Tire question

[13 Legion]

My buddy has T315/70/ R17 tires on his JK. He’s had a small lift put on. The stance looks great. My question is he’s been told by separate ‘Jeep’ guys that the tires are 31’s and someone else said no 33s.

[Pete M]

neither seem to be correct as 315/70 r17 tires are 34.4" x 12.4"  in size.    

 

https://tiresize.com/tiresizes/315-70R17.htm

[krustyballer16]

Got a tape measure?

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[13 Legion]

Right Pete. We measured them yesterday and they were roughly 34 in height. So does that make it a 35? Just asking because when I hear 31’s, 33, 35s is that a standard measurement or is say a 31 actually taller or shorter than actual measurement. Thanks Krusty as well!

[Dzimm]

Tires are almost never exactly the height they are measured at.  Some companies run slightly larger than advertised and some slightly smaller.  At 34.4" it would either be advertised as 34", 35", or even 34.5" depending on the company that made them.  

[kryptronic]

They're basically 35s.  I debated on 315/75R17 vs 35x12.5x17 for my JKUR.  All the research I did showed the 315s as slightly smaller.  Very, very slightly.  Here are 35s on mine with a 2" OME lift and PSC flats:

 

 

FYI, they measure 34.25" installed on wheels with AEV specs at 32 PSI.

[DirtyComanche]

Metric sizes are metric sizes...  They don't always convert to a 'round' size in inches.

 

Metric sizes do seem to tend to be closer in size to what they're labelled as compared with inch sized tires.