I just bought my new '05 F-250 this last weekend. It is everything I hoped it would be except that it came with the 17" rims instead of the 18's that I'd hoped for. I have found a great deal on an 18" tire/wheel combo and was wondering how it would affect my performance and mileage? Has anyone else made this switch? Thanks.

 

it will affect your speedo reading, as to peformace some of the guys that know better will help you out shortly.
right now in the factory 18 not to manytires to use and every ones seeems to dislike what they get.
mine has 17 inch and i love them . but i will admit i just drive mine . as long as it rolls i'm ok.
best of luck with what ever you do.

 

Keep your 17" you have more options. I got 18" on mine and the factory tires stink I hope there are better options by the time these wear out. As far as performance just check the outside diameter and try to get tires close and you will be fine
I always ran 33" tall tires on my 96 which had 16" rims in fact ran BFG MT most of the time great tires in snow
I think my 18" rims now have 32" or33" tires I have to check. The one thing the 18" does do is fill in the wheel well nice but other than that I can't see any real benefit to having them plus they cost more to replace.
Glen
05 F-350 4x4 Reg Cab PSD 6Spd.

 

The tirerack.com has most tire brands and their specs. Plug in the tire sizes and compare the RPM (revs per mile) for the 17" & 18" tires. That would be the easier way of determining the difference (if any) in the tire circumference and how much (if any) your speedo will be effected.

I agree with the other two guys......keep your 17" wheels unless you have money that is burning a whole in your pocket plus the selection of available tires is much better.

 

I guess I am not clear as to what rim size has to do with performance......I thought that it was tire size that changed performance. A 35" tire is, give or take a little with the different brands, a 35" tire.....doesn't matter if it is on a 16" or 22" rim. So unless there was enough of a weight difference I can't really see how the rim diameter would affect performance.....now if you increased the width of the rim, that possibly could affect performance some, but probably nothing to noticable.

Now, for something helpful in trying to make a decision....I don't think you would really notice a difference between 17s and 18s so unless you just wanted a different look or a wider rim I would just stay with the 17s. Or possibly there is not a good selection of tires in one of those diameters......I havn't looked to heavily into either one of those sizes to know.

I myself am currently running 35's on 16x10 rims. I have gotten use to seeing trucks with bigger rims now and am thinking about 35's on 20's. Not the best set up for going offroad, but I don't really end up offroad much. We'll see......something tells me once I look at the money end of it I will just stick with the 16x10s I currently have.

 

Thanks for all your input. The reason I am asking is because the tire calculator says that the stock tire (275-70R18) on the 18" rim turns 4.9% faster than the stock tire (265-70R17) on the 17" rim (at 2000 rpm in overdrive, that's a difference of 3.5 mph). I won't do a lot of towing, so I'd prefer to drive a little faster while trying to keep my rpm's down so that maybe the engine will last a little longer. With the old '97 PSD, I went to a much taller tire on the stock rim, but I noticed that my fuel mileage actually went down (maybe because I was turning a larger, heavier tire) and I lost a lot of towing power. I'm just thinking that with this current idea, I would lose what fuel mileage I would gain because the tire is wider and heavier (3 lbs each), just as it is taller.