[CeeYeezy]

So my question is just that? I'm looking at buying a wheel tire combo. The sizes are as such:

Front wheel- 18x9
Front tire- 245-40-18

Rear wheel- 18x10
Rear tire- 265-35-18

If I'm not mistaking I thought the middle number is the tire wall height. If so why would the rear tire have a smaller wall height, if anything shouldn't it be larger. Im afraid it will leave a large gap in wheel well? What's your thoughts?

 

[GoT midlife CS]

As proposed the circumfrence of the rear is 1.3" smaller than the front. With a 275-35-18 in the rear it is only .4" smaller. The over all height would be 25.7". sidewalls would be 3.9" in the front and 3.8 in the rear.

Some other possible combos:

255-40-18
285-35-18 - Rear circumference is .6" smaller - overall tire height is 26"
4" sidewall front, 3.9" in the rear
or

For even more side wall

255-45-18
285-40-18 - rear circumference is .2" smaller - overall tire height is 27" - same as the overall height on the new Brembo cars
Both have 4.5" of sidewall.

I don't know what selection of tires are available in these sizes, but on paper they seem to work pretty well.

 

[fordboy 3.8]

the middle number is an aspect ratio of the first number for example the in the 245/40 the 40 would be a percentage of 245. the wider the wheel the lower the number to keep it from rubbing

 

[CeeYeezy]

Thanks for both Replies. It makes sense now. Appreciate it!

 

[s197inthe208]

So my question is just that? I'm looking at buying a wheel tire combo. The sizes are as such:

Front wheel- 18x9
Front tire- 245-40-18

Rear wheel- 18x10
Rear tire- 265-35-18

If I'm not mistaking I thought the middle number is the tire wall height. If so why would the rear tire have a smaller wall height, if anything shouldn't it be larger. Im afraid it will leave a large gap in wheel well? What's your thoughts?

Just so you know, the 245 40 will look small on the front of an s197. I used to have that size, and I wasn't happy with it at all. And a 245 wide tire on a 18x9 might be pushing it as far as stretched tires go. Just keep in mind the middle number is always a percentage and is relative to the width.

 

[Muckerpuck]

They will look a little small. in a 35 side wall and affect your speedo.

In the front 255 45 18 is the common size for this rim.
And back 285 40 18 is the proper rear size to keep your speedo close.

If you want a bigger rear tire look you can go up to a 285 295 size with a 45 side.. 285-45-18 and 295/45/18. this will give you that slighly larger tire in the rear.

Now on a 20 inch rim,, the 35s are ok.. I run a 295 35 20 in the back, and a 255 35 20 in the front. but no way would i go with any thing 35 on an 18 inch rim.

 

[CeeYeezy]

They will look a little small. in a 35 side wall and affect your speedo.

In the front 255 45 18 is the common size for this rim.
And back 285 40 18 is the proper rear size to keep your speedo close.

If you want a bigger rear tire look you can go up to a 285 295 size with a 45 side.. 285-45-18 and 295/45/18. this will give you that slighly larger tire in the rear.

Now on a 20 inch rim,, the 35s are ok.. I run a 295 35 20 in the back, and a 255 35 20 in the front. but no way would i go with any thing 35 on an 18 inch rim.

How badly would it affect the speedo? Would I be going faster or slower than what it says?