Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

1 - 7 of 7 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter · #1 ·
Hey all,

Right now I have Wrangler 255/75R17 on my vehicle but have had some issues getting into the mountains during snow storms.

I got an incredible deal on lightly used Cooper Discoverer 245/65R17 (on Jeep rims for $250 total). Unfortunately, these have a load index of 107 vs 113 on my ones right now. The folks at Discount Tire actually wouldn't even balance and put on the new tires as they said the load index was too low.

I can't find anywhere in the forums that talks about the minimum load index tire people are running. Any advice on if I can still use these? I don't typically carry large loads.
 

·
Registered
Joined
·
1,498 Posts
A load index of 107 can carry 2149lbs. Multiplied by 4, that's 8596lbs. That's way above the weight of your Jeep. At least I assume so. However, they (meaning lawyers) say to never run a load index less than what came on the vehicle from the factory. This is most likely why the tire shop won't touch them.

Sent from my SM-G955U using Tapatalk
 

·
Premium Member
Joined
·
8,335 Posts
Those tires are also smaller than the tires that came on your Jeep by a good bit. The 245/65R17 tires are about 29.5" tall while if you have a Sport it would have come with 245/75R17 tires which are 31.5" tall. If you have a Sport S, Sahara or Rubicon it would have come with 32" tires. (255/75R17 on Rubicon and Sport S, 255/70R18 tires on the Sahara except for several special editions which have the same tires as the Rubicon).

Are you sure the tires are winter rated tires? If they are they should have the snowflake emblem on the sidewalls. If they are an all-terrain tire then they are not a winter rated tire.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #6 ·
Those tires are also smaller than the tires that came on your Jeep by a good bit. The 245/65R17 tires are about 29.5" tall while if you have a Sport it would have come with 245/75R17 tires which are 31.5" tall. If you have a Sport S, Sahara or Rubicon it would have come with 32" tires. (255/75R17 on Rubicon and Sport S, 255/70R18 tires on the Sahara except for several special editions which have the same tires as the Rubicon).

Are you sure the tires are winter rated tires? If they are they should have the snowflake emblem on the sidewalls. If they are an all-terrain tire then they are not a winter rated tire.
Yup, they do have the snowflake emblem on them. Is it the end of the world to go from a 31.5" to a 29.5"?
 

·
Registered
Joined
·
2,316 Posts
Going to a smaller tire will effectively lower your gear ratio. It will also lower your ground clearance by about an inch.

The shorter tire will give you a bit more get-up-and-go when accelerating. Your highway RPM will be ~100 to 200 RPM higher and your speedometer will read about 8% faster than you're actually going. (Something along the lines of 65 on the speedo when you're going 60)..

The speedo error can be corrected with a programmer like the AEV Procal, or the Superchips Flashcal. There is also a popular phone app called JSCAN that works along with a suitable OBD interface.
 
1 - 7 of 7 Posts
Top