20 inch tires/wheels vs 18's

[v10kenj]

Sorry, I know this is getting to be an old topic, but I might have an opportunity to swap out my 20 inch tires/wheels for some new or slightly used 18's for little or no money. These are the pros and cons as I see it: Cons 20inch wheels/tires look better Cornering probably a little better 20 inch rims that I have are straight, and tires good (no flat spots) and balanced Pros A little better payload (about 100lbs) with the 18's Softer ride on street Better off road ride and more wheel protection More tire options and cheaper cost to replace A little backround info: I have a 2011 f150 4x4 6.2 liter lariat purchased new a couple months ago. Original tire/wheel combo were 18's, but these were swapped by the dealer (someone else wanted 18's not 20's) who put the 20's on my truck prior to purchase. Do you think it's worth swapping the 20's for the 18's. Will the ride quality on street driving be better? I think this would be my main criteria for doing the swap. I'm probably not going to do much off road driving and I will only tow/haul once in awhile. That said, I don't want to be substantially limited by a pretty looking wheel. Also do you have to update the PCM and or do an alignment for the changover. Thank you for your feedback.

[YoGeorge]

If the overall diameter of the tires is the same, no PCM change is needed--in fact, if the new 18's are the same size as the OEM wheels on the truck, it may be better calibrated if the 20's are slightly different in diameter. There are formulas for calculating tire diameter based on size, but you could just go to Tire Rack and check the actual mfr specs for diameter for the exact brand and model tires. If the overall diameter is the same, you are picking up an inch in sidewall height which gives a safety margin like we have discussed in the other thread.

You will have to have the TPM (tire pressure monitor) system updated for the new sensors, assuming that both sets of wheels have the right sensors and you're not dismounting. If they are from the same year of truck, chances are pretty good that the sensors will be the same type, but you will have to have the TPM system taught to recognize the new set of sensors. If you are getting new 18" wheels and tires that have to be mounted, pulling the sensors out of your 20's would save the reprogramming step.

As for ride quality, with a given tire pressure, it should be a bit better, but there are a lot of variables here. For instance, if the 18's have E rated tires and the 20's are P rated, it could go the other way. But with the same type of tire and air pressure, you will have more sidewall flex and more air cushioning available and the ride will be better. But owners of F150's who have done this changeover would be better qualified to speak directly to this.

Alignment is independent of wheels and tires unless you are doing something crazy like changing wheel offset by a significant amount, which you are not.

Good luck,
George

[fordman19762003]

overall diameter of the stock tires that Ford offers in the 20"&18" sizes are virtually identical, so there wouldn't be any need to recalibrate anything. I personally like a smaller wheel because you get more sidewall height which helps soften the ride a little and does protect your wheel a little better.

[ri_truck_guy]

Originally Posted by fordman19762003

I personally like a smaller wheel because you get more sidewall height which helps soften the ride a little and does protect your wheel a little better.

Can't imagine the thing with a softer ride....with the 20s on mine it already feels like I'm driving my recliner....

[YoGeorge]

Originally Posted by ri_truck_guy

Can't imagine the thing with a softer ride....with the 20s on mine it already feels like I'm driving my recliner....

I think this is a good summary. If I were in your position, I would probably not change from the 20's to 18's primarily for ride quality--it will not make a world of difference. I would personally lean toward 18's for practicality, cheaper tire replacement, and durability. But don't take a bath on the proposed trade, either.

That said, I have put high end Michelin tires (MXV4's on cars and LTX M/S's on trucks) on vehicles and have had them completely transformed in terms of ride, so the ride quality aspect of your deal may well depend on the precise tires you have in 20" and the precise tires you will get on the 18" wheels.

I don't know what wheels you have now or what you propose trading into. If you have the "chrome clad" type things, I personally hate them because they remind me of $10 Walmart hubcaps and prefer painted or clear coated aluminum wheels, but again, this is MY taste, not yours.

Good luck,
George

[v10kenj]

It seams like the ride is a little floaty, having to steer just a small amount too much. I thought the 18's might not just have a softer ride, but a better overall ride as well if that's what the truck is designed for. I do know what you are saying though about tires making a big difference. I had a 2003 f250 with the Pirelli STR all seasons and eventually replaced them with Michelin LTX's. It made a huge difference in ride quality.

[ri_truck_guy]

I should be a little more clear about my earlier post....I'm pretty darned stoked about the way mine rides and handles with the factory Pirelli 20s. It handles quite well, and I wouldn't want a softer ride.