My Tundra Has Oversized Tires

[Dave1194]

Bought a 2017 Tundra to tow my travel trailer. Previous owner installed new LT 285 60R20 tires on it. My door panel says it should have P275/65R18 tires. This Spring I'm going on a cross country trip and I'm wondering if it would pay to sell the bigger tires for the sake of better gas mileage.

I'd appreciate some discussion.

[consolenut]

If the shift points in the transmission and the speedo are correct it shouldnt be huge diff. The bigger tires will equate to lower rpm in over drive etc. if it still keeps the engine in its useable torque curve your okay. If it lugs then you either need stock tires or re-gear

[kdauto]

Originally Posted by Dave1194

Bought a 2017 Tundra to tow my travel trailer. Previous owner installed new LT 285 60R20 tires on it. My door panel says it should have P275/65R18 tires. This Spring I'm going on a cross country trip and I'm wondering if it would pay to sell the bigger tires for the sake of better gas mileage.

I'd appreciate some discussion.

Why do you think you'd be getting better gas mileage, because of the 10mm width difference?

Your current tires roll at 104.3% of the OE size. It's not in the norm but it shouldn't create "real" fuel consumption increase. If you use your vehicle odomoter for calculation it will be off by 4% or so.

[CCrew]

Check the load rating on your tires. Many 20" are P-Rated ones and are lower rated than a equivalent LT tire, and LT's in 18" are much more available than in 20". Been there done that :-(

[kdauto]

Originally Posted by CCrew

Check the load rating on your tires. Many 20" are P-Rated ones and are lower rated than a equivalent LT tire, and LT's in 18" are much more available than in 20". Been there done that :-(

He stated the stock tires are P rated 18s and the replacements are 20" LT's.

[JIMNLIN]

The LT E are mpg and power killers for when towing for several reasons. A couple would be...

The biggie is tire weight especially with a small block gas engine. Looking at tire rack show the 20" LT E in that size can weigh in the 55-60 lb range vs 42-45 lbs for the OEM 18" P tire . Thats a lot of parasitic drag for the engine to over come. Someone shot their self in the foot by using a 3600 lb capacity
very heavy LT E on a 1/2 ton gas truck.

Next is the 20" LT E in the size you mention is around 33.5" diameter vs 32" for the 18" P tire. This lowers rpm at a given speed and just like heavy tires can be a power robber . This really shows up when towing.

20" wheels are popular now with the 1/2 ton crowd...and the LT E should sell quick to 3/4 and one ton truck owners. Sell them on CL or ebay and go with the 18" OEM. You will be surprised how much more peppier the truck will be. I know I was on a used 1500 chevy 5.3 6 speed tranny 3.73 gears some one had installed 20" LT E in place of OEM 17" P tires with around the same weight/tire diameter differences.

[kdauto]

Originally Posted by JIMNLIN

The LT E are mpg and power killers for when towing for several reasons. A couple would be...

The biggie is tire weight especially with a small block gas engine. Looking at tire rack show the 20" LT E in that size can weigh in the 55-60 lb range vs 42-45 lbs for the OEM 18" P tire . Thats a lot of parasitic drag for the engine to over come. Someone shot their self in the foot by using a 3600 lb capacity
very heavy LT E on a 1/2 ton gas truck.

Next is the 20" LT E in the size you mention is around 33.5" diameter vs 32" for the 18" P tire. This lowers rpm at a given speed and just like heavy tires can be a power robber . This really shows up when towing.

20" wheels are popular now with the 1/2 ton crowd...and the LT E should sell quick to 3/4 and one ton truck owners. Sell them on CL or ebay and go with the 18" OEM. You will be surprised how much more peppier the truck will be. I know I was on a used 1500 chevy 5.3 6 speed tranny 3.73 gears some one had installed 20" LT E in place of OEM 17" P tires with around the same weight/tire diameter differences.

No disrespect meant but your answer is just plain wrong. While every single ounce of weight added to a vehicle will affect performance and handling, a measly 15 to 20 lbs per wheel on a 2.5-3 ton vehicle means nothing!

Many 1/2 tons come with pretty damn heavy and wide LT tires anyway. I switch many 1/2 tons with P rated to LT E-rated 10 plies, much heavier sometimes...NO issues.

I will agree that widening up a tire a few inches and a very knobby, aggressive tire will rob "some" power I doubt the average human will notice. Fuel mileage will suffer a few percent. As I told the O.P. his mileage correction factor is off by over 4%. If he bases fuel economy calculations off it that will be off as well.

I would not recommend him going bak to wimpy ¨P-rated tires unless he's only planning to tow a 2 person popup. A 10 ply vs any 4 or 6 ply tire will greatly increase towing stability if inflated and sized properly.

[keymastr]

People suggest putting E rated tires on half ton trucks as a measure of increasing towing stability all the time but I have done it and noticed no difference. If your half ton truck is handling your heavy trailer poorly enough for you to consider spending $1000 on new tires, save your money and buy a 3/4 ton truck. You could spend a fortune on tires, overloads, airbags and whatnot and still have a vehicle that has a weaker frame, brakes, rear axle, wheels etc. and in my experience made so little difference that I really wished I had just not bothered and gone straight to the right vehicle in the first place. Would have saved plenty of cash for sure and the difference in how it tows is night and day. No way that half ton would have ever felt this secure.

[Cumminsfan]

Originally Posted by keymastr

People suggest putting E rated tires on half ton trucks as a measure of increasing towing stability all the time but I have done it and noticed no difference. If your half ton truck is handling your heavy trailer poorly enough for you to consider spending $1000 on new tires, save your money and buy a 3/4 ton truck. You could spend a fortune on tires, overloads, airbags and whatnot and still have a vehicle that has a weaker frame, brakes, rear axle, wheels etc. and in my experience made so little difference that I really wished I had just not bothered and gone straight to the right vehicle in the first place. Would have saved plenty of cash for sure and the difference in how it tows is night and day. No way that half ton would have ever felt this secure.

x2. BTDT 2010 F150 145" WB, Max Tow with 1857 lbs CCC. Added Super Springs and E rated Michelins.
Moved to a Ram 2500 CTD CC LB and only using a cheapo EAZ-Lift it towed better than the F150 using an EQ 4pt sway WDH.
The weight and longer WB of the 2500 kept the 2500 in charge of the TT.
TT was 31' @7200 lbs with 900 lbs TW.
I noticed very little difference when adding the tires and SSprings to the F150.

[kdauto]

Well, in the case of the O.P. he already has LT tires on now. If it drives OK and speedo error, clearance etc. is acceptable I say drive it.

I still have my 1994 Suburban, it's always had LT E-rated on it. Some of these had P rated I'm pretty sure but the ride just feels soft and less stable.

When one already has a truck capable of pulling a load 1000-1300$ or so is a cheap investment to keep using their truck vs buying a new one. I'm not talking about trying to haul 15 000 lbs with a 1/2 ton either! I did NOT mention any other modifications.

[aether_one]

Keep the tires.
If you find your transmission constantly downshifting out of Top Gear (overdrive), manually shift to the lower gear and keep it there.

In the manual transmission world it was normal to always tow in 4th gear in a 5 speed transmission.

[Dave1194]

Thanks to everyone for the debate and feedback.

As I mentioned, I just bought both the trailer and the Tundra and have had neither out on the first trip. So I suppose I should wait and see how the current tires perform.

In addition to the larger tires, the previous owner had also upgraded the suspension, installed a cold air intake, installed a high-flow dual exhaust system, and a Bully Dog (although I'm unsure yet of the BD benefit).

In defense of the Tundra, however, Toyota doesn't rate their trucks as 1/2 ton, 3/4 ton, etc. Toyota simply gives you the tow capacity. On my truck, which is equipped with the tow package, the capacity is 9,800 pounds. My trailer gross weight is 9,800 pounds, but I seldom have full tanks, and don't carry a lot of unnecessary stuff around, so I'm good there.

Every Tundra owner I've talked to assures me I'll be happy with it as a tow vehicle.

Anyway, you folks are great! You always give me more, and valuable, information than I anticipate.

[kdauto]

Originally Posted by Dave1194

Thanks to everyone for the debate and feedback.

As I mentioned, I just bought both the trailer and the Tundra and have had neither out on the first trip. So I suppose I should wait and see how the current tires perform.

In addition to the larger tires, the previous owner had also upgraded the suspension, installed a cold air intake, installed a high-flow dual exhaust system, and a Bully Dog (although I'm unsure yet of the BD benefit).

In defense of the Tundra, however, Toyota doesn't rate their trucks as 1/2 ton, 3/4 ton, etc. Toyota simply gives you the tow capacity. On my truck, which is equipped with the tow package, the capacity is 9,800 pounds. My trailer gross weight is 9,800 pounds, but I seldom have full tanks, and don't carry a lot of unnecessary stuff around, so I'm good there.

Every Tundra owner I've talked to assures me I'll be happy with it as a tow vehicle.

Anyway, you folks are great! You always give me more, and valuable, information than I anticipate.

As we repeat time and time again, you'll run out of payload capacity and especially rear axle weight rating of the tow vehicle far before the "tow rating", which is almost marketing speak anyway.

I'd recommend you look at the yellow sticker in the driver door jamb and possibly weigh your loaded trailer at some CAT scales before going far.

[VanDiemen23]

In my experience the most likely potential issue would be overheating the transmission. if it has a tranny tempo gauge, make note of where it is before you start towing.

Does the tundra monitor trans heat and provide warnings?

I had a Chevy 2500 with the 700R4, highway gears and oversize tires (a bit larger size delta than you have but not big enough to require lift) and that thing would allow fluid out on any long climb, even when not towing.