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BobChill · 02-14-2019, 10:52 AM

This may be a dumb question but I can't find the correct answer. I have a 2015 Ram 1500 with crappy stock 275/60/20 tires. I want to replace the tires with Michelin Defender LTX M/S tires but the only 20" size that has E load rating is 265/60/20 so it has a smaller diameter. Are there any issues putting 265s on the truck? I assume the 275s aren't available with E load rating because of the taller sidewalls?

60sumtin · 02-14-2019, 03:48 PM

The crappy tires I assume is the Goodyear Wrangler HP? Those are the tires that came with my truck and I agree. Cooper makes such a tire you are asking about. There may be other brands but it was the first hit I came across. Other than your speedometer will be out they should work but talk to your tire dealer first.

bneukam · 02-14-2019, 06:55 PM

They do make a 275 65R 20 in a load range E.

60sumtin · 02-15-2019, 06:14 AM

Quote:

Originally Posted by bneukam

They do make a 275 65R 20 in a load range E.

According to this site there are a multitude of brands in that size to choose from.

BobChill · 02-15-2019, 08:47 AM

Quote:

Originally Posted by 60sumtin

According to this site there are a multitude of brands in that size to choose from.

Great site!

I've had Grabber HTS tires on a previous truck but I never towed more than small boats with it. I keep getting stuck on load rating and max PSI. The TT I buy will weigh in below 7k lbs loaded no matter what. I like the XL load rated Grabbers (plenty of weight capacity). The only other thing I'm stuck on is max PSI. Is it really that important to need up to 80psi for a 27' TT that weighs 7k lbs tops and a tongue weight in the neighborhood of 800lbs?

I can get a really good deal on the Michelin Defender LTX tires but the only way to get E load is to deviate from stock tire size... I'm never a fan of that. Everything in life is always more complicated than it appears... lol

60sumtin · 02-15-2019, 09:57 AM

Quote:

Originally Posted by BobChill

Great site!

I've had Grabber HTS tires on a previous truck but I never towed more than small boats with it. I keep getting stuck on load rating and max PSI. The TT I buy will weigh in below 7k lbs loaded no matter what. I like the XL load rated Grabbers (plenty of weight capacity). The only other thing I'm stuck on is max PSI. Is it really that important to need up to 80psi for a 27' TT that weighs 7k lbs tops and a tongue weight in the neighborhood of 800lbs?

I can get a really good deal on the Michelin Defender LTX tires but the only way to get E load is to deviate from stock tire size... I'm never a fan of that. Everything in life is always more complicated than it appears... lol

I'll refer you to the RV Tire Safety site. The link is specific to your question. It's operated by fellow member tireman9 who is a retired tire engineer. Lots of good reading for just about everything tire related. I say just about because its an ongoing blog.

BobChill · 02-16-2019, 11:11 AM

Figured I'd follow up with my thread in case other Ram owners run into the same puzzle with 20" factory rims. I'm going to have the Grabber HTS60s with XL load rating installed. I've read numerous posts from towing forums of other Ram owners going with the same tire. More load capacity that I'll ever need (3k lbs per tire) and a good highway tire as well (I had a set on a Suburban and loved them). If I was was towing a big/heavy trailer I would get E rated but my trailer loaded up will never exceed 7k lbs and tongue weight including hitch will be under 1k lbs. Grabbers should do the job nicely for what I need them to do.

SmokeyWren · 02-16-2019, 11:44 AM

Quote:

Originally Posted by BobChill

I want to replace the tires with Michelin Defender LTX M/S tires but the only 20" size that has E load rating is 265/60/20 so it has a smaller diameter. Are there any issues putting 265s on the truck? I assume the 275s aren't available with E load rating because of the taller sidewalls?

If you insist on Michelin Defender LTX MS, then Michelin does not make that size in an LT tire with load range E. Michelin does make that size in P-series which is close to equivalent to load range C of an LT tire.

If you want that tire in load range E, then you must either move up to size LT275/65R20E or down to size 265/60R20. Either one should work just fine on your truck. If your truck is a 4x4, then be sure to change all 5 tires to the same size.

https://www.tirerack.com/tires/tires...omCompare1=yes

How will size LT265/60R20E affect your truck? The difference can be estimated by the percentage change in the tire revolutions per mile (revs/mile).
New tires = LT265/60R20 = 640 revs/mile
Stock tires = P275/60R20 = 630 revs/mile

640 minus 630 = 10, divided by 630 = 1.6%.

So your effective axle ratio will be changed by 1.6%, and your speedo (compared to now) will be off by 1.6%. That's probably not enough difference to be noticeable. If you have 3.55 axle, it will "feel like" a 3.57.

BobChill · 02-25-2019, 10:31 AM

Quote:

Originally Posted by SmokeyWren

If you insist on Michelin Defender LTX MS, then Michelin does not make that size in an LT tire with load range E. Michelin does make that size in P-series which is close to equivalent to load range C of an LT tire.

If you want that tire in load range E, then you must either move up to size LT275/65R20E or down to size 265/60R20. Either one should work just fine on your truck. If your truck is a 4x4, then be sure to change all 5 tires to the same size.

https://www.tirerack.com/tires/tires...omCompare1=yes

How will size LT265/60R20E affect your truck? The difference can be estimated by the percentage change in the tire revolutions per mile (revs/mile).
New tires = LT265/60R20 = 640 revs/mile
Stock tires = P275/60R20 = 630 revs/mile

640 minus 630 = 10, divided by 630 = 1.6%.

So your effective axle ratio will be changed by 1.6%, and your speedo (compared to now) will be off by 1.6%. That's probably not enough difference to be noticeable. If you have 3.55 axle, it will "feel like" a 3.57.

I felt most comfortable sticking with stock tire size and had a set of General Grabber HTS60s installed last week. They have an XL load rating. Should be plenty for the TT I ordered (5280 dry / 7000 gvwr). I'm estimated a tongue weight + WDH = at or below 1,000 lbs. I've ordered new rear springs for the truck as well. Ram's ride like a car but over 50% of the miles on this truck will be towing so putting better springs is totally worth the tradeoff of a slightly rougher ride when unloaded. I'm the only one who drives the truck unloaded so there's nobody to complain about ride. I'll install the springs myself so for $225 it's a lot of bang for the buck and should keep my rig nice and level (and planted) when towing.