Tire radius

[Takket]

Hi!

When purchasing tires, how much does the radius matter?

My current tires are 235/55/R18. When I went tire shopping the website told me my car should have 235/60/R17

I thought... that can't be, because if I have an 18" Radius wheel now, a 17" wheel won't fit! But reading this it seems both tires can fit on my rims.

https://www.tire-reviews.com/Article/The-differences-between-17-18-and-19-inch-tires.htm

The difference is really only very subtle for traction/noise/comfort. Is that accurate? I'm trying to shop a few sites to find the best price and the 18" are about $40 more per tire, which I won't waste my money on if I don't actually needed it, but I want to make sure I'm buying something that fits!

This is for 2016 Ford Taurus SE FWD.

[Roland99]

1. Make sure you check the exact model type for your car.

Model, engine, options, etc. could have a sport pkg with bigger wheels

Or someone swapped the OEM wheels with larger.

Also, while the outer diameter may be the same, the height of the actual tire will not be the same as the inside diameter will be taller than the original tire

[Arger68]

2. Standard size for your

Car is 235/60/17. The 235/55/18 was an optional size. There's no way you can put a 17" tire on an 18" rim (or an 18" tire on a 17" rim). They may cost more but you'll still have to get the 18" tires.

[liberal N proud]

3. The 18 is the size of the wheel

18 inches is the size iPod the rim the tire mounts on.

If your car says it has 17 inch tires, you must stay with 17s unless you buy new rims for 18, then you need to check the profile or height of the tire and make sure it will have clearance.

It's always best to stick with OEM unless you are going for a different modifications.

[Hotler]

4. Look on the end of the driverside door for the tire size and preassure, there should be a sticker

from the factory, go by that and/or your V.I.N. (number) with you to the tire dealer. Some times when shopping online you can enter your VIN number to get the correct part. If you bought the car used it could have different wheels than what came with it. Go out and look at the side of the tire you have on there now.

[Takket]

9. there is a sticker, it is for 18". That's what I'll get :) Thanks!

[taxi]

5. the website has no mechanical experience

Last edited Sat Apr 15, 2023, 11:44 AM - Edit history (1)

As stated in an earlier reply, if your current tires are ..R18, then your rims are 18" rims and need 18" tires. With your car, the Taurus, you should have enough clearance between the tire and the fenders to fit just about any tire. Check out this site: https://www.goodyear.com/en_US/vehicles/Ford/Taurus/2016
It tells us that your car can have tires as large as 245/45/20.

To break it down it works like this: the middle digit, in this case 45, is a percentage. Multiply that by the first digit, the width of the tire - 245mm and you get 110mm. The 110mm is the height of the sidewall, a little less than 4-1/2 inches. That 4-1/2 is on both sides, so you end up with the rim width, 20", plus 4-1/2 twice, or 29"

Here is a site that does it for you: https://www.1010tires.com/Tools/Tire-Size-Calculator
On the left side is a box that defaults to By Vehicle, so go ahead and click Tire Size instead. Using this calculator with the big numbers above shows an actual size of 28.68"

If you are not into racing down the street and hitting the corners hard find yourself a nice set of 235/55/18's. They are for the Taurus SE and SEL and will be smooth and quiet.

eta: the 235's start at about $125

[patphil]

6. Unless you have a specific reason, use the size(s) listed on your current tires.

Some vehicles have different rim and tire sizes front to back for performance reasons.
For example, Corvettes use different sizes front to back:

https://www.iseecars.com/car/chevrolet-corvette-wheel-rim-size

[Wounded Bear]

7. Sounds like you may have after market wheel rims...

If so, you must match the size of the tire to the size of the rims. Otherwise they won't fit or seal. Any decent tire shop would tell you this.

If you have 18" tires now, you would have to buy new wheels to fit 17" tires.

[Hugh_Lebowski]

8. Long and short, the radius is not optional, need R18 tires for 18" rims

The other two options can be a little flexible as they basically describe how high off the rim the tire will end up sitting aka 'the profile' of thick it looks when viewed from the side. This affects ride and traction and 'performance'.

Best thing is to stick with what the sticker in the door jam says assuming you know they're still 'stock' rims.

And don't cheap out too much. The el-cheapos of many brands ... suck. Generally, the sidewalls will be thin, which allows the car to sway more. Especially if the car is heavy. You'll feel much less in control when driving esp turning, braking, and uneven pavement surfaces will throw your tracking off more easily.

[Takket]

10. i checked, i need the 18". Thanks for the replies everyone!

[Hermit-The-Prog]

11. Check the current tires for the DIAMETER of your wheels.

Don't go by door stickers or owner's manual unless you're certain those texts match the wheels on your car.

[Takket]

12. The current tires are 18. Which is why I was confused the website was telling me 17

But the sticker is 18 too.