Originally Posted by rdowning
I My stock tire size is 265/75R16, I am running 315/75R16s. Will these oversize tires affect my towing/ rear end gearing/ etc. in any way? Should I go back to stock tires? Any ideas or suggestions.
The percentage change in tire revs/mile = the percentage change in rear axle effective ratio, speedo and odo error.
Stock tires are about 655 revs/mile. 315s are about 600. 655-600 = 55, divided by 655 = 8.4%.
So your 3.73 axle ratio will "feel like" 3.42. Not a drastic change, but enough to feel the difference.
Your speedo will be 8.4% slower than with stock size tires. So an indicated 70 MPH will be an actual 76 MPH on Officer Bob's radar. So either have your speedo corrected, or else use a GPS to tell you what indicated speed = the speed you want to cruise at. Your odometer and trip meter will also be slow by 8.4%. So a 400-mile trip will actually be 433.6 miles. And 40,000 miles with the tall tires will be an actual 43,360 miles
Your tachometer will also be off by 8.4%. 70 MPH with stock tires and a calibrated speedo should be 2,000 RPM. But with the 35s, engine RPM will be only 1,832 RPM at a true 70 MPH per the GPS.
Whether you need to tow with stock-size tires depends on the terrain and the weight of your wet and loaded trailer. If the truck struggles to make a long grade of a hill or mountain pass, then you'll probably prefer the stock size tires. But if you're always towing on flat ground with the wind behind you, then the tall tires may be okay.
Also, what would be the best, and lowest cost anti sway bars/system to use for this set up?
The best usually costs more than the cheap stuff. You can add friction sway bars for about $120 each - plus some welding to add the small ball to the ball mount.
Trailer Hitches, Hitch Accessories, Hitch Wiring
But they are barely adequate for anything. Much better is the Reese Dual-cam sway control system, but it ain't cheap. Mine cost me over $700 including the WD hitch, ball mount, shank and dual-cam sway controller. If you already have a WD hitch that will fit, the dual cam sway controller is only $194.
Draw-Tite, Reese Dual Cam High Performance Sway Control 26102
If you don't already have a WD hitch that will work with the dual cam sway controller. I would start from scratch and buy a new Reese Strait-Line WD hitch with the dual cam controller already built in.
Strait-Line Weight Distribution w Sway Control - Trunnion Bar - 12,000 lbs GTW, 1,200 lbs TW Reese Weight Distribution RP66074
Note that the shank is not included at that price, so add about another $120 to that price to get a good adjustable shank.
Or better yet, the ProPride hitch system is a wonderful unit and well worth the more than $2,000 cost. I'm saving for one now.
Trailer Sway Control Hitch Guaranteed to Eliminate Trailer Sway - ProPride 3P