I'm looking at replacing my soon-to-be-bald factory tires, and have been looking around on Tirerack for a good replacement tire. I have 17's with Dunlop Wintersport M3's on them for the winter, so I'd like a summer-only tire. The only problem is that I can't find a reasonably priced summer tire with the "XL" load rating (I don't want another set of RE050A's), the only tires in 215-45-18 that carry the 93W (1433 Lb) service description and XL rating are the Kumho Ecsta ASP and the Pirelli P-Zero ... both all-seasons.

I'd like to go with the Kumho Ecsta SPT, but it has a service rating of 89Y (1279 Lb). Does anyone think that this would be an issue?

It looks like going from 93W to 89Y will drop the total load rating from 5732 Lb (1433 x 4) to 5116 Lb (1279 x 4).

Any thoughts or experience would be appreciated.

You need an XL tire in the stock size. If you go up to a 225/45 you will be fine with a 91 or higher rating. A 225/45 tire with a 91 load rating holds the same weight @ 35PSI as a 215/45 with a 93XL rating at 38PSI. IMO, a 89 load rating will work, but you will notice the poor handling over an XL. I think there have been some posts about the SPT's with 89 rating not working well...

Also, a lot of us have found the 225/45 tires actually make the speedometer more accurate...

I run 225/45 Dunlop M3's on the stockers for winter and 225/45 S-03's on the MB's for the rest of the year.

Thanks, Insane. Great info!

No problem.

Here is a handy chart for determining load requirements and what PSI to run. (thanks posttosh)

http://www.tiresafety.com/images/Tire%20Re...nt%20Manual.pdf

Page B14 is what you want...

if i were to go with a 235 (on a different rim obviously) what is the minimum load rating I should look for?
edit: thanks insane!

The XL designation (not a "rating") does not mean what you probably think it means. At any given inflation pressure that is approved for a 91 or 93 load index tire, a 91XL or 93XL tire actually will have a lower load capacity than a standard load (SL) 91 or 93 load index tire.

That said, any tire that has a load index lower than 91 (SL or XL) should not be fitted to a Mazda6.

Yeah, the XL refers more to the stiffness of the sidewall and inflation pressure than it does the load rating. The 91 rated, XL 225-45 General tire probably should be run at a higher inflation pressure than the stock tire (say 40-41# rather than 38) but otherwise appears to be working well and wearing fine on my car. And since it cost less than 1/3 of the RE050, even if it wears a little faster it'll save me money. No perceptible difference in dry weather performance and actually better performance than the stockers in the rain. I run the summer tires on RX8 wheels and the winter Blizzaks on the stock wheels (also in 225-45 because I can run the higher performance Blizzaks in that size vs only the W series in 215-45).

Why would you run a higher pressure with a 91 load rated 225/45 tire? A 215/45 93XL @ 38PSI holds 1314lbs. A 225/45 91SL tire holds the same weight at 35PSI. As for sidewall stiffness, I disagree. The Potenza S-03's I have are 91SL and the sidewalls are noticeably stiffer than the stock 93XL RE050A's. I personally think the load rating has more to do with the load the tire carries at a given pressure than sidewall stiffness...hence the term load rating.



Isn't the main difference between SL and XL ratings that the XL's can increase their load capacity past 35PSI to 41PSI while the SL's top out at 35PSI?

http://www.tirerack.com/tires/tiretech/tirespecskey.jsp

If by load rating you mean Load Index, 91, 93, then that number designates the maximum load capacity of the tire. It will be at higher pressures for xl's vs sl's.

For a given Load Index (lbs), like 91, the xl type requires more psi to match the Sl type. XL is a stronger, higher pressure tire design to meet any specific load spec, vs the SL tire.

I looked this up on the chart of inflation pressure vs load rating and those weren't the numbers (of the chart I found anyway). They indicated that for a 91XL to get the same load rating as a 93XL (given the change in overall size) I had to increase inflation pressure. Do you mind my asking where you're getting your numbers? I'll see if I can find the chart I used (there was a little extrapolation IIRC because it didn't specifically list the application I wanted). That said, my understanding is that XL tires DO require a higher inflation pressure for the same load rating but allow tend to have shorter, stiffer sidewalls so get better performance than the SL.

"... The 91 rated, XL 225-45 General tire .."

are you sure it's XL, not sure that combo exists ??

the euro 225-45 XL is a 95 load index.