Tires size changing tow capacity

[Pap and Mimi]

I installed Nitto G2 (35-12.5-20) replacing 275-65-20. The Nitto advertise a height of 34.52 instead of the 35. GPS says my speedometer is still correct and I don't notice any difference in the way the truck drives. Looks like your tire is actually 35, so you have a 1/2 inch radius difference or roughly 3% difference, which probably wont be noticeable.
Check the load ratings of the 2 different tires and if the "new" tire has a lower rating, see if there is an option for a higher ply version. (Nitto offers E and F ratings)

If the "new" tire has a higher load rating than the old, you don't get to add to the truck load rating,(yellow sticker rules) but your "safety margin" increases.
If the "new" tire has a lower load rating than the old, you may be reducing the truck load rating. (depends on what is the weak link driving the truck load rating...tires, wheels, frame, axle, springs....)

[marine6805]

What that chart is missing is the weight of the old tires and rims vs. the new tires and rims.
That is a starting weight to changing tow capacity.
IMHO . . . .I really don't think you will accomplish enough "tow capacity" to justify the cost.

[marine6805]

Larger Tires has a direct effect on payload . . . .larger tires (most likely wheels as well) is more weight on the truck . . . .which is factored into payload.

[NB Canada]

Larger Tires has a direct effect on payload . . . .lager tires (most likely wheels as well) is more weight on the truck . . . .which is factored into payload.

Technically wheels and tires (unsprung weight) don’t add to payload but I know what you mean

[marine6805]

We can agree to disagree. . . .but my basic premise is that he will NOT realize enough difference in payload or tow capacity to justify money spent!

[NB Canada]

We can agree to disagree. . . .but my basic premise is that he will NOT realize enough difference in payload or tow capacity to justify money spent!

I am quite positive he is NOT trying to change payload or capacity through tires

I am sure the “money” he is spending is purely for looks and he was only concerned if it would hurt his tow ability

[Scott'n'Wendy]

. . .larger tires (most likely wheels as well) is more weight on the truck . . . .which is factored into payload.

Nope...not even a smidge.....affects handling.......not payload...

[Longshhm]

Okay. No theory here; real world application. And a note up front - all wheels and tires cited are very close to the same load rating, and all are the same brand.

I have a Ram 2500 Limited. The truck came with 20” wheels and 285/60/r20 tires; the previous owner had changed the tires to 275/65/r20. Stock Ram wheels (on most models) are 18” and come with 275/70/r18 tires. For my truck, the gear ratio is 3.42, which is based upon the standard 18” wheel/tire combination.
The 20” wheel/tire combination has a 1” larger diameter than the 18” wheel/tire combination, and it has 1” less tire sidewall height. The effect is that the 20” combination effectively lowered my gear ratio, I’m guessing to about 3.21 or so, making the truck work harder to pull weight. The shorter sidewall also made for a much stiffer, more uncomfortable ride.
When it came time to replace the tires, I got a set of 18” OEM wheels and the stock 275/70/r18 tires.

Here’s the net result of all this:

The change did not impact the speedometer enough to warrant any recalibration. My GPS and speedometer seem to agree on my speed more than they did before.

The gear ratio is back to the spec 3.42; the truck seems to have more pulling power and better acceleration. My fuel mileage has also improved by an average of about 1.5-2.0 mpg; makes my wallet happier.

The taller sidewall in the 18” tire has helped smooth the ride, and DW is really happy about that.

Anyway, that’s my experience and $.02 worth; take it for it’s worth, comment as you will. Just don’t expect any debate on it from me. Best wishes for you.

[Scott'n'Wendy]

The taller sidewall in the 18” tire has helped smooth the ride

This is what I'm thinking about doing.

[lorend]

Does it affect tow capacity?

I do not see anything that says what you will be pulling so my questions is; Are you really looking at tow capacity (towing a trailer/ bumper pull) or are you looking for payload capacity (towing a fifth wheel). It is easy to get the two confused in a conversation. I do know that on my truck I have slightly larger tires than stock. I do not know if it affects towing capacity. But I do know that my tire weight ratings, old and new tires, is higher than my rear axle weight rating. So it does not affect payload because my axle is the weak link on the rating.