New Tire Research
 

I need to replace the tires on my 8 and am thinking about going with the Advan A048. Problem is the closest size is a 225/40-18. Not a real big difference. Should fit with little or no problems right? Might make my speedo off...

Any suggestions? Does anyone think the Advans are overkill... or not worth it?
Any input please.

Advans are good tires, but you realize that they are R-rated tires right ? will give you great traction but you will be lucky if they last 8000 miles. Most of the Advan tires have treadwear rating of 100 & below. If you have lowered your car the difference should not be that noticable, but if it is stock the wheel well might look a bit big with the lower profile tire (with no drop).

I would be impressed if you made it to 5,000 miles with these tires. The tire size will be shorter than the stock tires but it will also have less load carrying capacity which becomes a safety issue. I have listed the specs for both tires below for you.

225/45/18
26.1" tall
Max load capacity at the recommended 32 PSI - 1281 lbs per tire

225/40/18
25.1" tall
Max load capacity at the recommended 32 PSI - 1025 lbs per tire
Max load at maximum air pressure 51 PSI -- 1235

Basically what this means is that if you are running the 225/40/18 at 32 PSI you will be 1024 lbs short of what Mazda states you need for an RX8. Even at maximum PSI the tires would be 184 lbs short in load capacity. If you did decide to do this and tried to run the tires at the max PSI you would end up wearing the tire unevenly and it would make the car feel very stiff.

If you are stuck on Advans, wait for the Advan Neova to hit our shores this spring. Suposed to have more grip then the Falken Azenis and >140 wear rating.

yes... thank you for your input guys.

is that difference due to the different size? or the specific tire itself?

If you like the idea of a super sticky tire, you might wait a bit and check out the new Falken Azenis RT-615. They will have a 245-40-18, which is an appropriate size. The previous generation Azenis was a near-R tire, and although the RT-615 isn't availbale yet, it should be similar. And they should be affordable as well.