I'm looking into getting some Falken RT-615, and putting them on the stock rims. Would there be any bad side effects from running 255/40/18 instead of the 245/40/18. The 255s are closer to the stock diameter of the 225/45/18s, but the 255s slightly to big for the rx8s 18x8 rim diameter. I also noticed there is only a 3/10 of an inch diffence in tread width between the two, is that even worth the added trouble.

http://www.falkentire.com/rt615_sizes.html

 

the difference wont be that big anyways. I wouldnt worry about it.

I wouldnt put 255s on the stock rims, they are outside of the recommended sizes and therefore you increase your risk of tire failure exponentially.

I would go 235s on the stock rims, when I had 245s on them they felt too "squishy"

 

my understanding is that the widest you can go on the stock wheels is 245

 

I used to run with 245/40's. But after looking at the chart, the 235's are 4 lbs. lighter each. You only give up a couple of tenths of an inch in tread width. And a lot cheaper too. That most likely will be the one I will get for next year.

 

The smallish width OEM 8" wheel wouldn't give needed 'bracing' to the tire sidewalls of the 255s, resulting in softer, more squishie handling compared to wider wheels, also possible excessive tire edge wear unless they were overinflated to kick the center tread out. Not to mention the extra weight. Best to stick to recommended sizes or go to wider wheel to take advantage of the extra tread. 235s work fine, however or 245s on 9" wheels too.

 

If I were getting the RT615s I'd get the 235/40s too. The weight savings I feel negates the difference in tread width and the rolling diameter is so close to that of the 245/40s.

 

order from vulcantire.com and you get free RT-615 tire totes.

 

NICE i want those tire totes

 

I want tire totes too.

 

The RT-615 actually offers OEM size of 225/45. So wouldn't it be a perfect fit to stick to the original size? Having said that, I do see the 235/40 offers some marginal advantages in terms of wider section width and lighter weight.

But my main concern is safety. Does it safe to mount the 235/40 on OEM rims which is 8" wide. Anyone here has run the 235/40 on track event and how does it feel??


TIA
Pete

 

Considering a lot of manufacturers run 235/40s on 8" wide wheels, it's not an issue at all.

 

I didn't mount it, my dealer did, they lasted lots of track days over for 1 year and they felt fine. I'm confident others have done the same. How could they ever be unsafe?

 

Since your main concern is safety I'm sure you throughly researched the subject.

Then you would know, because the first thing you did was go to the tire manufacturers website, is:

that the following applies

225/45/18 fits 7.0-8.5
235 fits 8-9.5
245 fits 8-9.5
255 fits 8.5-10.0
295 fits 10.0-11.5
265 fits 9-10.5
275 fits 9-11.0
315 fits 10.5-11.5

I'm glad we agree on the subject.

 

After some more research on the web, I think I'm ready to get my 8 a new set of 615. Instead of the OEM size of 225/45/18, I'll go for the 235/40/18. Actually, I think the specification on the Falken 235/40 is even closer to the OEM Potenza 040 224/45 than the Falken 225/45.

On rotation, since the 615 is asymmetrical, is that mean you can only rotate them front to rear on the same side. i.e. front <-> rear on the left and same for the right?

 

Incorrect. Asymmetrical tires can be rotated side to side, it's directional tires that need to be kept on one side of the vehicle only.

 

I see. Thanks for correcting me LionZoo So the correct way is to transfer between front left and rear right and the same go for the others?