I want to get new tires installed on my 96 Ram 4x4 3/4 ton auto, which carries a mid-70s Alaskan camper (around 2000 lbs). Tires still have good tread on them but are a bit old (show some cracking between treads), and I'd feel safer heading out on long trips with new rubber.

Stock-sized tires are on the truck now (245-75-R16). Since the truck is not geared for highway (rev's around 2000 at 60mph with the OD), I thought maybe I'd go a bit bigger to bring the revs down a bit at highway speeds. I was considering going 265-75-R16 (about 1.2" bigger). I was told by tire shop it could affect cornering, and obviously the speedo. Obviously, I am getting 10 ply E rated tires, all-terrain. Advantage of going stock is that I could use 1 (or 2) of the existing tires as spares, otherwise I'd have to buy set of 5.

Would you advise me going that bigger size, or stay stock? Thanks.

 

I would get the taller tire. Yes, it will affect cornering a bit. But you're already top heavy with a camper, so you know how to drive a vehicle like that.

More side wall will give you a slightly softer ride.

But you might not improve mileage any. It's like having a numerically lower rear gear ratio. The rpm's are lower, but it takes more torque to spin them.

You will also need more brake effort to get the same results. If you think you have marginal brakes now, it will get worse.

 

I run 285-75-16 E rated Michelin and I don`t have any problems towing my 10,500 lb fiver. Taller tire helps keep rpm`s down I think. My .02

 

Thanks guys. Someone else suggested I check my wheels, because a 265 should supposedly be installed on 7-8" wheels, and he figures I probably have 6-6.5" on my truck (stock). Hadn't thought of the wheels, which would add to the cost of going taller obviously....

 

Actually, I probably have the steel-chrome wheels and not the alloy as I was thinking. I took pictures of the spare tire rim (original with the truck?) as well as one of the wheels that's on there. Plus pictures of the ruler measurement of wheel width (from edge to edge I read about 7.5", and not 6.5" as the door jamb label would indicate). Maybe I'm reading it wrong.

Anyway, all this to hopefully allow someone to tell me just what size wheels I have on there, so I can choose suitable tires to match.

 

p.s. Just checked the build sheet for my truck and it states 16x6.5" wheels, so no matter how I measure it, I have 6.5" wheels on there. Sorry for confusion.

 

Have you checked your speedo with a gps with your current tires? On my truck with the stock tires, 67 on the speedo = 65 actual. With my 225/70 19.5's, the speedo is dead nuts on. I'd go with whatever tire puts your speedo the closest. I don't think a size one way or the other will make any noticable differences on handling/fuel mileage, etc...

 

No haven't checked speedo with GPS.

For the marginal benefits that a slightly taller tire would provide, I have decided to go with the stock tire size (245/75/R16) for the replacement set. I don't need the extra weight capacity that the bigger tire would provide, and my wheels would be the limiting factor anyway. That way:
(1) I don't have to buy a spare tire and can use two of my old ones as good spares
(2) I don't have to worry about any speedo (hopefully it's accurate!) or other issues and
(3) the truck won't be an inch and a half higher to get into the cab, or the camper in the back (high enough as it is! :-)
Thanks to all for your thoughts and suggestions.