Tire size vs towing

[muttmachine]

I want to get bigger tires but i also tow a 24' camper (toyhauler) thru the sand. The tires im thinking of are 285 17's . Does anyone think that this will impact my towing ability very much?? I have an '04 DC TRD.

Opinions appreciated

Mutt

[2000LtdKen]

Originally Posted by muttmachine

I want to get bigger tires but i also tow a 24' camper (toyhauler) thru the sand. The tires im thinking of are 285 17's . Does anyone think that this will impact my towing ability very much?? I have an '04 DC TRD.

Opinions appreciated

Mutt

Mutt,

I have a 2000 Tundra Limited 4x4 and when I put on some Michelin 265/75-16 I did notice a power decrease when towing my toyhauler on the local mountains. I just put on JBA headers and my truck feels "alive" again. Will be towing again this fall with the new setup.

Ken

[RockyMtnRay]

Originally Posted by muttmachine

I want to get bigger tires but i also tow a 24' camper (toyhauler) thru the sand. The tires im thinking of are 285 17's . Does anyone think that this will impact my towing ability very much?? I have an '04 DC TRD.

Opinions appreciated

Mutt

It mostly depends on what aspect ratio those 285 17's are and, to a degree, what type of tire they are.

If the 285s are a low profile 60 series tire, then there will be almost no effect at all on overall tire diameter and thus no real effect on towing capability.

OTOH, if (as I suspect), you're thinking of getting all terrain tires that are truly larger diameter for better off road (sand) capability, you're gonna really hurt your towing capability. For instance, if you choose a 75 series 285/17, the tire diameter is about 33.8 inches. Since the the stock 265/70R16s are 30.6 inches, that's a 3 and a quarter inch diameter increase... which will cause an 11% drop in torque. It's the absolute equivalent of regearing your axle to an "economy" 3.6 ratio from the stock 4.10. The truck will be very sluggish without a trailer in tow; with the trailer hooked up you'll be hardpressed to even get moving on even moderate grades. Acceleration on freeway onramps will be downright scary...you'll likely only be up to about 55 when you're at the end of the on ramp.

Furthermore, if the new tires are of the all terrain variety, they'll have softer sidewalls and bigger tread blocks than the stock tires...both of which will further reduce effective torque getting to the ground and substantially increasing the likelihood the trailer will cause big time side-to-side sway at the rear of the truck. Toyhaulers can be evil to tow anyway because of they have so much mass behind their axles when loaded...putting soft sidewall tires on the truck will just make the sway situation worse. Be sure you are using the best sway control you can get with your weight distributing hitch.

Short of trying to tow with at least one spark plug missing from the engine, I can't think of many ways you could hurt your truck's towing capability more than putting on 285/75R17 all terrain tires.

The only way you'll be able to get back resasonable towing performance after changing to 285/75R17 tires is by regearing your differentials with either 4.56 or 4.88 gears. And that will cost you somewhere around $1500 for parts and labor...give or take a couple of hunded. The usual trick of installing headers (7% gain...and about $1100 installed) will only get you back about 2/3 of your lost torque.

As I've explained before to many people, without spending a huge amount of money, you can get a great off road truck or you can have a great tow vehicle. But it's very hard and very, very expensive to have a truck that's both great offroad and a great tow vehicle.

[ericb]

What criteria does determines rather a Tundra has 245/70-16 or 265/70-16 tires. My 2003 AC has the 265's, but I have an extra set of wheels and wonder if the 245's would make towing my 4565lb unloaded weight travel trailer a little easier up the mountains. I wouldn't bother switching tires for weekend camping, but wonder if it would be worthwhile for 1-4 week trips where I'm putting some distance on it.
BTW, thanks to Ray for giving me the info to limit my wife on trailer size. She was pushing hard for a 5100 lb unloaded trailer, but I held firm.
Eric

Originally Posted by 2000LtdKen

Mutt,

I have a 2000 Tundra Limited 4x4 and when I put on some Michelin 265/75-16 I did notice a power decrease when towing my toyhauler on the local mountains. I just put on JBA headers and my truck feels "alive" again. Will be towing again this fall with the new setup.

Ken

[RockyMtnRay]

Originally Posted by ericb

What criteria does determines rather a Tundra has 245/70-16 or 265/70-16 tires. My 2003 AC has the 265's, but I have an extra set of wheels and wonder if the 245's would make towing my 4565lb unloaded weight travel trailer a little easier up the mountains. I wouldn't bother switching tires for weekend camping, but wonder if it would be worthwhile for 1-4 week trips where I'm putting some distance on it.

First, sorry about the delay in responding to your question...I was gone the past week.

Yes, assuming the 245s are the same aspect 65 ratio, their diameter is roughly an inch...or 3.5% smaller than the 265s. That translates into 3.5% increase in torque at the rear wheels...roughly the same as changing from a 3.91 axle to a 4.0, or doing some mod (like a muffler swap) that provided about a 10 ft-lb torque gain. The effect will be pretty subtle...you'd notice very slightly higher speeds on grades and a very slight reduction in propensity to downshift. But given that the 245s may not have as much load capacity...and the scarcely noticable gain in torque, I'm rather doubtful if the cost of a set of 245s and the hassles of mounting/dismounting the stock tires at the beginning and end of each trip would be worth it.

BTW, thanks to Ray for giving me the info to limit my wife on trailer size. She was pushing hard for a 5100 lb unloaded trailer, but I held firm.
Eric

Welcome. Glad to be of help in helping preserve your truck's longevity and family safety.