Kevinmacd

doubleux - think you have that backwards the front load ratings are less then the rears, has to be smaller tire. Please tell me how these tires exceed the N spec? If you look at the latest N spec for the rear tires they have a load rating of 98. Sumos carry a 94.

doubleurx

No, I have it correctly:

PS2's (N3) front max load rating is 1235 lbs, 88Y for the 225/40/18 & rear max load of 1653 lbs 98Y for the 295/30/18

Sumitomos front load rating is 1389 lbs, 92Y for the 225/40/18 & rear max load of 1477lbs, 94Y for the 295/30/18

So what I said above is correct. The Sumitomos front tire actually has a higher rating than the PS2 front tire.

FWIW all the other tires mentioned in this thread the Kumhos and Hankooks all have identical ratings for the rear and higher for the fronts. Oddly enough the "N" spec tires generally give you a lesser load rating than all the tires mentioned with the only exception being the rear tires in the Sumitomos.

doubleurx

On another note. I'm sure glad I took the Cayenne to work today. It looked like it might start snowing at lunch time. Right now it is a white out with 2" on the ground! - will summer ever arrive?!

Kevinmacd

doubleeux - sorry gotta disagree, in the 295-30-18 rears, the N3 spec has Bridestone S-02A and Michelin Pilots and Pirelli Assimet. All carry a load rating of 1653. I think you are refering to N0, N1, and N2. Of which these are older specs! So like I said the Sumo do not meet the more current N3 spec with N4 popping it's head up. The rears have to carry the majority of the weight,, so it would be logiacl that the higher load carrying would be on the rears.

Mikelly

You guys are really splitting hairs here... And I've been running the Sumitomos for a year without issues, even used them on track...

Some of you guys bow at the foot of Mother Porsche, which is fine. But please don't bash the rest of us for choosing to go alternative routes, especially when we've proven that the "non-approved" tire works just fine.

Mike

Kevinmacd

That's my point Hankooks are non approved but carry the same specs as the N3. So it's a no brainer!

doubleurx

I think you need to re-read my post. The specs I am quoting are N3 PS2's. I don't disagree with you on the rears. The front PS2's (N3) have a lesser rating than the other non - N rated tires. The rears are matched in load rating by all the other tires mentioned except the Sumitomos which have a higher rating for the front and a lower rating for the rears.

In short - Sumitomos in a size 225/40/18 have a higher load rating than the N3 PS2's. Sumitomos in a size 295/30/18 have a lower rating than the N3 PS2's. Hankooks Ventus V12 and Kumho Ecsta XS have in a 225/40/18 have a higher load rating than the N3 PS2's and match the load ratings for the 295/30/18.

doubleurx

Actually Mike - the point I am making is the "N" rating is not something to be concerned over as most high performance tires meet or exceed the load rating. I refuse to pay the "Porsche" tax on tires when there are tires out there at nearly half the cost that easily performe as well. I run Kumho XS in 235/40/18 front and 315/30/18 rear and couldn't be happier with these tires.

larry47us

OK, I'll acknowledge that the Sumitomos don't have as heavy a load rating on some other tires. But based on the ratings, the Sumitomos will carry 1,477 lbs per tire max. If we multiply that out, that means that the rear tires are able to carry a max of 2,954 lbs. The maximum rear axle load of a 2001 Porsche Turbo is 2,601.3 lbs. That is what is listed in my owner's manual. It even has that weight asterisked, saying that "The maximum gross weight must not be exceeded."

That being said, the Sumitomo tires are capable of carrying 353 lbs more than the axle is designed to carry. The fact that the N3 spec says 1,653 is totally irrelevant, since the total weight of the car (empty) is 3,394.9 pounds. The total carrying capacity of the N3 spec tires is 3,306. Only 88 pounds less than the TOTAL WEIGHT OF THE CAR!! I guess if you are doing wheelies in your Turbo, you need to worry. For us more normal drivers, the N3 spec is meaningless, and the Sumitomos work just fine, thank you.

larry

doubleurx

You can also feel comfortable that your front end can handle a higher load than the N3 spec. While most of the weight on these cars is in the back, the weight transfer to the front on hardbraking entering a corner is something to consider. As I have said before - the N rating is a Porsche tax and nothing more.

Kevinmacd

N spec has a correlation on how porsche setup their cars for optimal handling, hydoplanning, etc. with that said, the load rating has a direct correlaton on handling. A higher load rating has a stiffer sidewall, stiffer sidewall = better handling. You can discount the N spec, but the reason I keep bringing up the load carrying capibility to match the N3 spec or higher even though the tire is not "N" certified, means it just wasn't tested by Porsche. Yet you can get the same results by matching up to the N spec, and in this case load capacity, speed rating etc.. Load capacity exceeding the vehicle weight is only part of the equation.

SSST

Boy you guys have picked the nit, transformed it into a molehill, and then turned it into a mountain. LOL!

Enjoy your new tires Larry.

FWIW, I have Sumis on my truck. They were basically knock-offs of the Pirelli Scorpions it came from the factory with. I only drive it when I need to haul something, hunt, or fish so I was just looking for serviceable. They are fine, but have less dry pavement traction than the Pirelli's did. I can smoke them off the line without any problem. I couldn't do that with the Pirellis. Ride and wet traction are good though.

I'm sure the rubber compounds are different between truck tires and Porsche tires, but it would make me leary before buying Sumis for the P. Just my .02

larry47us

SSST - Sometimes you just have to create some fun out of the technical BS. I love it when threads go hyper-esoteric and then totally over the top. I pride myself on being the one that went TOTALLY OVER THE TOP on this thread.

larry

doubleurx

Yes I did also, but i was simply clarifying my post as for some reason, I must not have been very clear with the data? Still trying to figure out what was difficult to understand, but O'well.

c32AMG-DTM

It appears the N3-spec load ratings account for the unusual weight characteristics (F to R) of 911 variants. The vast majority of vehicles produced are front-engined, resulting in a majority of tires having higher load ratings for common front-fitments (when OEM calls for a staggered fitment). So, since Porsche is pretty unusual in it's tire requirements, a few tire manufacturers custom-spec a tire to match.

Having excess load capacity in the front should, in theory, cause a more jarring ride than is necessary for the amount of weight being supported, because the sidewall is stiffer than needed. Having insufficient load capacity in the rear might cause issues under severe driving... for example, it would be interesting to measure and know the amount of force experienced by the LR tire coming out of the corkscrew at LS. Would it exceed the rating of the Sumis? Don't know.

Matching too much in the front with too little in the rear could, in theory, cause unusual handling characteristics at odds with Porsche's factory implementation, suspension tuning, brake bias and tuning, etc.

All that said, I honestly don't think anyone short of Rohrl would probably notice...