Load rating...how important?

[mysleeper6]

I've seen this mentioned before, but I searched and could not find what I was looking for. The stock tires on the MS6 are rated at 93, which translates to a max load of 1,433 lbs. per tire. I am currently on stock wheels with Kumho Ecsta 225/40R18's. When I bought them, I was thinking the stock load rating was 92 (1389 lbs), so that is what the Kumho's are. I am buying summer tires to put on RX-8 wheels and would like to go 235/40R18. Most of the tires I like have a load rating of 91 (1356 lbs.). I am lowered on RPM Streets.

How critical is the 77 lb. difference between the stock tires load rating and the load rating of the tires I am considering, given that 1356 X 4 = 5424, and the curbweight of the car is only(!) 3589 lbs?

[wannabe]

unless you are REALLY fat or have a lot of really heavy stuff to pull around, you should be fine.

[mysleeper6]

That was what I was thinking as well. I max out at about 175, so I think I'm good.

[Igve2shtz]

The car stock weighs around 3600 lbs with a front:rear weight distribution of about 60:40, which means the front tires hold 2160 lbs and the rears about 1440.

So, under static conditions, the each front wheel will hold 1080. So you still have a 300 lb safety margin on each front wheel, and about 500 lb safety margin on each rear wheel.

So, unless you are moving a circus cross country in your MS6, you will be fine.

[vrspeedemon]

I've been running Rx8 rims with 225/45/18 Kumho spts with a load rating of 91 for over 10,000 miles now on my MS6, haven't had any problems so far.

[mysleeper6]

The car stock weighs around 3600 lbs with a front:rear weight distribution of about 60:40, which means the front tires hold 2160 lbs and the rears about 1440.

So, under static conditions, the each front wheel will hold 1080. So you still have a 300 lb safety margin on each front wheel, and about 500 lb safety margin on each rear wheel.

So, unless you are moving a circus cross country in your MS6, you will be fine.

Thanks. I wasn't sure if those were static numbers, or if I had to apply a dynamic force equation of some sort.

I've been running Rx8 rims with 225/45/18 Kumho spts with a load rating of 91 for over 10,000 miles now on my MS6, haven't had any problems so far.

Thanks. Good to know.

I guess I'm going to go ahead and do this. If I have to, I'll roll the fenders, but it looks like I won't have to.