Wheels and tires..........

Does anyone know if 245x50x20 tires would be about the same diameter as 245x60x18?

Here's the scene: Our Lincoln MKX has the low profile 20" wheels and tires. I'm getting fed up with them. The insides of the wheels are flat and don't allow snow, ice, dirt, etc. to sling off while they're spinning or drain off when they're stopped. The junk just slides to the bottom of the wheel and creates a lump that throws the wheel out of balance.

I made a wand on a garden hose with a 90 degree fitting on the end to reach between the spokes and wash the insides of the wheels out, but that even isn't always fully effective.

MKX's also had an 18" wheel that has a slope in the rim that would allow junk to sling off while spinning, and run off when stopped.

I just put $700 worth of new Cooper tires on the thing last fall, but--per the Internet, salvage yards sell the 18" wheels for about half of what the 20 inchers go for. If I knew it would solve the problem, I'd consider going to the 18" wheels. I'd think I could at least break even on the deal. Plus the vehicle might even ride a bit nicer.

I know, those low profile tires are all the rage, but engineers and people who promote them must not realize that vehicles ARE driven under conditions other than dry pavement.

Looks like the difference is pretty small


Tire Comparison Site

According to the tire size calculator posted by Burt, the difference is small.
We changed out the wheels & tires on our camper from 16.5 to 16?s,
and the surprise we got into was the speedometer was off,
Speedometer said 55, actual 65 mph.
Cured the problem with a different drive gear in the transmission.
1985 model Chevy.
I don?t know what will happen in a late model vehicle that uses computer,
on SIL?s late model Ford pickup, the transmission would not shift properly, after changing tire sizes.

This link below is from a discussion forum so most of the stuff (like here) is reader opinions ..... still some interesting replies though.
18

Make sure the smaller diameter wheels will clear the brake calipers.

That is kind of strange in itself. We had a 16 MKX on 20 in aluminum and ran it 65,00 with never a mention of balance or mud problems. I just went out and looked at the 18 sitting in the carport. It is on 20 inch aluminum and there is enough room for me to stick my hand in beside the wheel and brakes and wheel has right smart of what I would call taper or slope. The shiny or outside tapers at least two inches to the back. I run 20s on my f 150 and yes tires cost more but sure helps sell one. We both (wife and I ) trade on two year intervals , usually around 65,000 miles.

Thanks!

I saved that.

245/60R18 was the other OEM size for the 18" wheel on that vehicle. As you already know the two sizes share nearly identical dimensions except wheel diameter.

10 minutes at the dealer to tell the computer the difference.