Tire Size vs. Towing Ability????

[DennisG01]

I read up on a lot of posts about this topic, but still a question remains: Currently I have 245/75's - but if I move up to 265/75's, how much of a differance will I notice while towing?

I thought there was a chart somewhere on TDP, but couldn't find it.

Thoughts/experiences?

[moondoggie]

Good Day!

For tire diameter info, go to The Diesel Page.com Member's Area (http://www.thedieselpage.com/password.htm) (Click in colored text)& click on Paul Rowland's RPM/Gearing Calculator Excel Spreadsheet: & do what it says (look before you click).

For the effect on weight capacity, look on the tire sidewall.

Blessings!

Brian Johnson, #5044

[markrinker]

I have recently done this very swap on both trucks. 3% bigger, so minor speedo/odometer error and no negative effect on towing that I can measure.

Maybe a little more rolling resistance, but worth it for the ride and they look better in the wheelwells.

[DennisG01]

Thanks Mark & Brian. I checked out the spreadsheet - tell me if this makes sense:

tire size 245 = 2160 rpm @ 70mph w/3.73 gears

to get tire size 265 to equal same rpm, I changed diff. gear to 3.87. So, tire size 265 would perform the same with 3.87 gears as 245 with 3.73?

That's a difference of .14 (3.87 - 3.73). Assuming I don't actually change my diff. gear, but only upsize to 265, would that theoretically make my diff. gear 3.59? (3.73 - .14)

I don't know, maybe I'm putting to much thought into this...

Mark, you said you didn't notice any difference? What type of weights/hills are you towing?

[markrinker]

Average towed weight of 6,000-8,000 lbs. Rolling hills of Minnesota and South Dakota. Read below for other mods on truck #2. Very happy with 265s.

Tried 31" rubber for pulling and don't think it would run hills well, loaded. I expect to run 65-70mph loaded at all times that traffic allows.

[moondoggie]

Good Day!

From the spreadsheet:

LT245/75R16 diameter: 30.47

[joed]

I actually do this swap every year as I run the stock 245s in the winter and use the 265s in the summer.

My conclusion is there really is no measurable difference in towing (pulling) performance. Not as much as pulling with the A/C on versus off, for example. It does seem more stable with the 245s, probably because my 265s are only Load C versus the E rating of the 245s.

Joe.