Oversized Aftermarket Wheels?

[timm9]

I did search but did not see anything remotely close to my question.
I have a 2011 double cab Dodge TCD that pulls our TT and just purchased a set of aftermarket wheels that are larger than the stock 17’s at 18x9 with -12 offset. I was ready to purchase new tires for the aftermarkets and then started wondering if the change will in anyway have a negative effect on towing or stability. The TT is a new Rockwood 2506S and I do have a WDH installed. I’m only going up one-wheel size but was curious if the larger size and offsets will change anything. Lastly, any recommendations for the new tires assuming the new wheels don’t cause issues?


Any feedback would be greatly appreciated…😊


Tim

[GOTTOYS]

The larger diameter will affect the final gear ratio. Adding more offset is never a good thing. It puts a tremendous strain on the wheel and axle bearings.

[upflying]

The -12" offset might cause the wheels and tires to extend past the side of the truck..a "fenders required " violation in California.

[jrk341]

Wheel size doesn't matter as much as tire size. More offset is never a good thing.

[ADOR]

This is true. Each vehicle is unique as to what gear ratio you need to re-gear to. I changed tire size from 35” to 38”. The off-road shop who worked on my H2 explained this to me and advised me that I need to re-gear my axles and also need to purchase a programmer to re-program the vehicle's computer to make it think that the engine and transmission is still running stock size tires and wheels. Also keep in mind that the bigger tire size will add weight to your vehicle, which will lessen your additional towing capability (adding weight to your Gross Combined Weight).

However, if your new wheels and new tires will be the same diameter as the STOCK tires, then “maybe” it will be OK.

Originally Posted by GOTTOYS

The larger diameter will affect the final gear ratio. Adding more offset is never a good thing. It puts a tremendous strain on the wheel and axle bearings.

[jrk341]

Larger diameter wheel will not affect final drive ratio if the diameter of the tires are the same. Example is, if you have a 17" wheel with a 33" diameter tire and an 18" wheel with a 33" tire they will turn at the same speed.

[robbiels7]

Isn't everything some kind of ventilation in California?

Originally Posted by upflying

The -12" offset might cause the wheels and tires to extend past the side of the truck..a "fenders required " violation in California.

[upflying]

Originally Posted by robbiels7

Isn't everything some kind of ventilation in California?

I just mentioned it because the OP mentioned "Sierras" in the avatar.
Tires sticking out way past the side of trucks is not an enforcement priority for CHP but you never know.

[Ejs4029]

Originally Posted by upflying

I just mentioned it because the OP mentioned "Sierras" in the avatar.
Tires sticking out way past the side of trucks is not an enforcement priority for CHP but you never know.

I never had a problem with CHP in CA with the Chevy 2500 HD that I had for 9 years

[Retired JSO]

The greater offset will put more pressure on the rear bearings especially when towing. How much I’m not sure. Ran offsets on a 68 Volkswagen back in my teen years and had to replace hubs and bearings after about 12,000 miles.

[robbiels7]

I couldn't resist. Here in Florida you can get away with just about modifications.

Originally Posted by upflying

I just mentioned it because the OP mentioned "Sierras" in the avatar.
Tires sticking out way past the side of trucks is not an enforcement priority for CHP but you never know.

[Jim34RL]

I am using Mickey Thompson rims on my truck with aftermarket tires. But in no way is my offset as large as yours is in fact it is zero offset. You will definitely have wheel BRG issues on the front end of your truck if the offset is a +12MM. Now is the offset -12MM if so, you might have interference with the steering linkage and you may need a lift!
Good luck!

[timm9]

Thank you all very much for your input! Based on comments and past experiences I will be abandoning the aftermarket wheels and will be looking to a larger stock wheel. I believe there are stock 20 inch wheels available that will not cause issues.


Thank you!


Tim

[Larry0071]

Your getting bad advice. +12mm is a half inch. A half inch will apply a bit more leverage on the front unit bearings, and instead of getting 150,000 miles from them maybe you'll get 120,000 miles... but it's no big deal. Besides, unit bearing do not catastrophically fail. You will get ABS/TC errors when the bearings begin to crap on you due to fine metallic material screwing with the pickup. You may get a growling sound as well. They are simple to replace. Your not going to self destruct the truck or the wheel bearings because of that 12mm.


You are changing the scrub radius. Shifting the wheel out on the center disk means that if you put the tire on sand and crank the steering wheel back and forth you will no longer be pivoting on the center of the contact patch. This is the scrub radius. From the OEM, you pivot in the center of that contact patch, or super dang close. Offsetting in or out will move that scrub radius to the inside and instead of the tire shifting radially on the center point (as factory) it will actually leave that center point and "scrub" forward and backward along a radial path.


Take a cell phone and place it flat. Set your finger on the center of the screen and rotate the phone like a tire turning. Your finger is the ball joint.\


Now move your finger off center to the left or right, your finger is still the immovable ball joint... your finger can not leave this position on the glass screen. Now move the phone (the tire contact patch) along the ball joint axis.... see what happens? The tire is forced to "scrub" for/aft instead of pivoting on that centered ball joint.


This makes for increased wear of steering parts, most notably at low or no speeds. Going down the road is a no/never-mind. Twisting around while backing the trailer will cause increased pressure from the tie rod ends to the rack/gear box.


This is similar to the wheel bearing issue. It's not some "Oh my goodness! Your truck is going to eat tie rods every year!!!!" kind of thing. But it will shorten the overall life of the effective parts by some unknown quantity.


Millions of folks have trucks with aftermarket tires and wheels. They do just fine. You will as well. Just be aware that there is always some ying and yang action taking place. Give and take. Nothing comes for free.

[upflying]

One other issue that might be important with oversized tires and wheels is a fuel mileage penalty. How much mpg will be lost ? Depends on a lot of factors..

[Larry0071]

Originally Posted by upflying

One other issue that might be important with oversized tires and wheels is a fuel mileage penalty. How much mpg will be lost ? Depends on a lot of factors..

There is increased rolling resistance due to the wider tire, increased rolling resistance due to any increased diameter that brings with it a lengthened contact patch, you have reduced mechanical advantage due to increases in overall diameter, and you have to overcome additional weight of heavier wheel/tire choices. So yes, you will drop some amount of efficiency. Likely you will not see huge changes from a mild tire/wheel combination change. I wouldn't recommend swapping to 37"x13.5" mud terrains.

[goduc]

I went from 245/70/17 to 275/65/18 on my Ram 2500 CTD. didn't notice any difference.
My speedo was off 2+ mph. I towed a 9300 lb 5th wheel for 4 years with them. Rock solid.

[Hersbird]

I personally think tires sticking out past the widest part of the fender or it's flair looks amateurish. Something you see in the high school parking lot. That's just my opinion and I fully support a variety of styles when it come to cars, so to each their own.
You can't argue when somebody nails the "stance" of a car or truck, no matter the make or model, it really completes the whole thing. Something Chip Foose always paid close attention to.
When the wheels and tires fit perfectly wheel wells anything looks better. This is hard for all the GM guys as they don't make square wheels LOL!

[Bobh1]

Have a 2015 Ford F150 and a 2019 Chevy 2500HD that both have aftermarket stuff. Ford has 35s with 5" lift and airbags. Chevy has 33s with 2" leveling. I prefer the stability of wider rims and tires. Does my fuel mileage suffer? In the Ford yes. In the Chevy, not so much. Chevy has the Duramax diesel. Removed both spare tires and replaced with train horns. Carry a plug kit and air compressor along with some slime.

[ppine]

You can compensate for the larger wheel size by going to a lower aspect ratio tire. You want the diameter to remain unchanged.

If you use a similar tire in a larger size you will increase the diameter and have a noticeable reduction in power.