TV Tires

[Fred L]

A bit of a different question as not entirely pertaining to towing. Am getting a new Tundra and there is a choice between 18in wheels and 20 in wheels. ie 275-55-20 or 275-65-18.

Both selections result in nearly the same over all tire diameters. Of course the 55 have a lower profile.
From a towing perspective - with P Metrics, presumably the 55 and lower profile would be preferable since there is less sidewall for flexing and less sway resulting?


In the same tire, but a 65 vs 55, so taller sidewall, presumably there would be a softer ride, more bump absorption? and when towing more chance of sway?



Then what happens if you go to a LT, E rated tire. Does the sway drop on the 65, ie 18 inch due to a stiffer sidewall? Does the 55 not absorb bumps as well?



So are the appropriate selections to get the best of both, the 55 low profile in a 20inch wheel with P Metric - and the 65 on the 18inch wheel in an LT E rated tire.



And since i spend a fair amount of time off the pavement, will probably be going with an AT tire. Probably the new Continental which I also have on my old Land Cruiser and really like and I believe would be available to me in all the above configurations.


Would appreciate your thoughts.

[r carl]

Check the price of replacement tires between the sizes.

[Fred L]

Same price for the p-metric ie 275 55 20 vs 2765 18

(may not be an LT in the 55, now that i checked)

Not sure I understand your comment.

[donrogers]

I have been down that road somewhat. I had OEM P Metric 275 65R18 on our F150 and found them to be a little squirmy so I replaced them with LT 275 65R18 E rated tires and I like them much better. I inflate to 60 lbs and find the handling to be much more precise than the OEM tires. The ride is not at all objectionable to us, although we do feel more firmness in the tires. I spoke with the helpful folks at Canam RV in Ontario before I made this switch and they suggested either the route that I chose or going with 275 55R20s. I would have had to buy new rims if going to the 20” tire so chose to stay with the 18”. I am sure you will get varying opinions on your questions, but I suspect the 18” tire may offer a little softer ride. I liked the idea of a 10 ply tire for hot summer-time traveling.

[dasher]

Similar question so I thought i would jump in here. I have a 2013 F150 5.0 that has Wrangler 265/60R18s and the over all diameter is 30.4. Replacing these with better XL or LT tires only will run about $950.00. I am looking at some 2018 tires and wheels the just came off a new F150. These are Hankook 275-55-20 with a diameter of 32.1. Basically new for $600.00 wheels and rims

My question is with a 2.55 axle ratio how much torque and I losing with this inch plus change in diameter?

We will be towing a 1999 Safari 25

[Fred L]

Not sure on the torque issue, but sounds like a great deal since the tires alone new unmounted are over $150 a piece.

[pteck]

My name is pteck, and I have a problem. I have an unjustifiable like for all things tires. Whether A/T, max summer tires, whatever.

To the OP, you understanding is correct. With each parameter and tweak, they all tend to lean the tire towards certain qualities. More sidewall generally means more flex. From P, XL, to LT, will go up in sidewall stiffness, load, and durability, yet less comfort. To an extent, the compliance can be adjusted with air pressure. So more pressure when under tow will help with added stability.

Also worth some thought is whether you want to go up in overall tire diameter too much. More diameter reduces gearing, but more importantly it will also reduce brake torque. You're not going to a 35" tire so it's just for your awareness.

A 20" wheel will certainly aid lateral stability. An LT tire, will again increase that stability. To answer your question, between your two choices, you can't really go too wrong. It's a personal and aesthetic choice at that point.

I have a Land Cruiser in Lexus guise (LX570), that generally uses the same wheel and tire sizes the Tundra uses. Not recommending you go as far as I have, but I have 20" wheels with 33.2" LT tires, size 305/55/20. Tows beautifully. Yet the premium suspension and NVH isolation of the Lexus keeps the AT tires so well behaved that you would never know they were aggressive off-road truck tires.

[slowmover]

Pickups and other crude suspension vehicles need all the stability help they can get. If it weren’t for radial tires, no one would drive one, they’re that bad.

As to pressure, if 60-psi isn’t justified by scaled weight values per wheel (solo; and again when hitched, WD applied), this attempt to tune the suspension only makes the poor-performing vehicle worse in steering & braking.

“Performance” pickup tires & wheels ought to be a foregone conclusion where they otherwis meet the load imposed.