I recently acquired a new (to me) truck. It needs new tires. The factory spec tires are 245 75 16s. The truck currently has 265 75 16s. Now I know that bigger tires look lots cooler and give me more ground clearance (in this case, about 5/8"!!). But are there any actual practical advantages? And what are the drawbacks? Obviously the flywheel effect and the additional weight of a bigger tire must have a negative effect on stopping distance and brake wear. Anything else?

If you have bigger tires, why did you buy them?

If you bought bigger tires, did you make any mods to the brakes to compensate?

Bob in LA
2000 Ram 2500 CTD 4X4 QC; No mods that I know of.

 

On my truck, the door sticker shows 245/75R16's, but the build sheet I got from the dealer lists the 265/75R16E as the optional tire size from the factory that was on it. As to the size difference, I don't think any brake mods would be necessary until you get a lot bigger tire than a 265.

 

If you don't plan on offroad work the bigger tires are mostly for looks and a waste IMO gotta love a set of 42" tires that have never seen so much as a puddle. To each his own I supose

 

The weight rating on bigger tires is higher. Check what you are going to be hauling and make sure the tires can handle it if you decide on the 245's.

Michelin 265's 3415 lbs @ 80 psi
Toyo 285's 3750 lbs @ 80 psi

Other than that on a 4x4 the 245's look a tad silly IMO. The wheel wells just seem empty and the 245's look like golf cart tires. I would also try and find a truck with them on in and take a look at it.

Jim

 

The best reason I know of, besides additional ground clearance, is to compensate for a final drive ratio that is too low (too high numerically). That is precisely the reason I have 285/75/R17s coming to replace my 'O5 6-speed's 265/70/R17s.

 

On some brands, going up in size in the same model lowers the load rating. On Coopers, for example, the small tire is load range E, while its larger brethren are load range D.

Discoverer STT LT265/70R17 121 Q 0 E OWL 7.0 - 9.0 8.0 10.8 31.9 8.25 3195 18
Discoverer STT LT285/70R17 121 Q 0 D OWL 7.5 - 9.5 8.5 11.5 33.0 8.85 3195 18
Discoverer STT LT295/70R17 121 Q 0 D BLK 7.5 - 10.0 8.5 11.8 33.45 9.4 3195 20.5

All three have a capacity of 3,195 lbs.

 

Bigger tires are for mud or for looks. In theory, with a properly sized rim a bigger tire has a higher load rating but that is not always true. It also changes your final drive ratio so that you have a numerically lower ratio which isn't as good for hauling so the two work against each other.

Some people increase tire diameter to try to bring their rpms down. On the highway, this can help a little but it also increases your windage so it doesn't help much. Around town it actually hurts your fuel economy due to increased rotational inertia.

The real reason for big tires is mud. You get more ground clearance and a wider contact patch. If you don't mud, you probably don't need big tires.

 

Mine came with 265's and I try to stay with them, or 235/85's (same diameter but narrower for snow/mud). They fill the wheel wells much better and the wider footprint gives better wet traction.

load range is all you need to worry about- most tires are available in load E in both 265 and 245.

 

Please make sure you get an LT rated tire, not a P rated.

 

Better Traction. I had 235/85/16's on the 91' and it would just spin them away the 285/75/16 on the 01' offer better stability and better traction. The small hit in city mileage I took (1mpg on average) is worth it to me.