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Discussion Starter · #1 ·
I just ordered, but haven't mounted, the Sumis in 245s and 315s. There seems to be some negativity on this board surrounding these tires.

They were $570 compared to $825 for the Kumhos. They seem to be pretty close (7.5 vs 7.7) over the hundreds of ratings on tirerack.com

Further, I traded our Kumhos for Sumi HTR Z II's on my Porsche and they've been a much better tire, especially when there is a little rain on the pavement.

Just wondering if there are any silent supporters of the Sumis out there. If not, I might eat the shipping and trade them in for the Nittos or otherwise.
 

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interesting question.

mine are awful. 12,000 miles and they are very worn. granted, i have two track days and eight autocross days, but what's most significant is something strange about Sumi's: they wear in the center.

following the 1psi/100 pounds rule, i run 22psi year round. tires worn in the center means over-inflation but still the sumi's wear that way.

as far as price, the prices have come down a LOT since i bought my tires 6 years ago. an extra $255 for all four tires is a bargain!

people say Khumo's wear out, but my Sumi's have already dried out. i need new tires very soon.

.
.
 

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Discussion Starter · #3 ·
Thanks. It seems like the members who are satisfied with the Sumis are those who are using them for a non-track tire (my intended purpose). In retrospect, I might have gone with the Nitto 555s, but the Sumis are already on the way.
 

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I've run both Sumitomo HTR-Z and Kumho XS. The big question is what do you plan to do with the car?

If you are just cruising the Sumis will do just fine but they are not a performance tire by any stretch of the imagination. They're honest and will not bite (no pun intended!) meaning that their grip is very limited but they let you know it. They hate heat and turn greasy when pushed at all above 80 degrees but since their ultimate grip level is somewhat limited anyway they aren't severely impacted by cold. They are much harder than their treadwear rating would lead you to believe and will last a long time if you don't slide them. I ran the snot out of mine for about 6,000 miles and slid them a bunch and they still had ~ 70% tread left on the fronts and 50% on the rear when I pulled them off.

For more spirited use, autocross and track days the Kumho XS is a better choice. I'm starting on my second set of them after running the first set darn near to the cords in 7,000 miles which included hundreds of auto-x runs and a number of track days. They love heat and even when competing on 90+ degree days I never did get them TOO hot. They really drop off below about 60 degrees though; fine for street use but you can't push 'em too hard at low temps until you get some heat built up. They did not "go off" and in fact their grip actually increased as they wore. I had no reservations or second thoughts about going back with them again.

So, in a nutshell:
Street use only...Sumitomo HTR-Z
Performance use...Kumho XS

Cheers,
Jeff
 

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My experience with Kumho street tires is that they're junk and I'd just as soon drive on the bare rims. I wouldn't run them on an econobox, nevermind a decent car.

I haven't driven the Sumitomo, but that's because I have heard and read a lot of the same negative feedback you are getting.

The Nittos (555 and 555DR on the rear, 245 and 315 widths) on my FFR have performed and worn well. I'll be due for a new set, but it can wait for the spring driving season. I'm also a big fan of Yokohama tires, which have invariably been top quality for me.

Cheers, John
 

· Not a waxer
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My experience with Kumho street tires is that they're junk and I'd just as soon drive on the bare rims.
That's kind of a broad statement John. Which Kumho and on what vehicle?

Jeff
 

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That's kind of a broad statement John. Which Kumho and on what vehicle?

Jeff
True enough... I bought a BMW M-series that had a set mounted on some plus-size wheels, which I promptly pulled off and replaced with Yokos on the proper OEM wheels. When I was younger, dumber, and saving bucks in stupid places, I put a set of Kumhos on a 911 that I used to own. Sorry, don't remember the models -- the 911 was 10+ years ago. I may have already disposed of the ones from the Bimmer, but I don't remember -- will have to check the back of the shop. In both cases, they were some of the worst-handling and noisiest tires I've ever driven, and a solid lesson in "you get what you pay for."

But hey, opinions are like belly buttons -- your mileage may vary! :)

Cheers, John
 

· 1st RFM/FFR Legacy Winner
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I run Sumis. Have over 16K on the fronts (7 years) with maybe another 2K left on the tread life. The rears wore the centers out at 13.5K. They aren't a great tire but the price is right. I use them for street only and have not found the cornering limits on back roads yet. They don't make any squealing when the get near the limits or when the rears spin. The only reason I run the is the price.

Greg
 

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Where the Rubber Meets the Road... Adhesion is Good

Ya git what ya pay fer....
Had Sumi's Now have Kumo Xs. I can now drive the car as I had hoped to be able to ..... With the power I have, I am now able to hook-up and goooooo !
 

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Tires are not where you want to save money. Get the best tire you can find. They're the only thing that is keeping you from flying off the road.

If you drive like there is an egg under the gas pedal, sumis will suffice.

If, however, you have some power and a heavy foot, get the Kumhos.
 

· section 8
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Tires will wear in the center if you do not have a wide enough rim for the tire. I have both Nittos in 315dr and Sumis in the 315 on a 10.5 rim no center wear. The nitto's stick better (duh) and the sumi's smoke is a lot cheaper . also the drag 315's have 5+k on them and are not bald yet , includes dragstrip runs on a different car. Bob
 

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Like Jeff, I too have had both on my Cobra and I can tell you they're as different as night and day. I ran the Sumi's for 5 years and always thought traction was very limited, but I didn't know what I was missing. Last spring I switched to Kuhmo Ecsta XS's and wow, what a difference. Sooo much more traction, allows you to drive much more confidently on the twisties. Only negatives are less life, and they tend to throw up more debris from the road since they are so sticky. One positive about driving on the slippery Sumitomos, you learn the limits of adhesion better/faster, IMO. After driving on skates for years, I think I'm able to gather the car up faster when it tries to bite me.
 

· FFCobra Craftsman
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I have no problems w/ my Sumis after 6 yrs or so. Maybe they don't offer the traction that others do. But I run autocrosses to get my rocks off and am kind of a grand father on the street. Yep, I do a lot of 10-70 blasts in a straight line. I drive faster than most on a country road but that is still well below the cars max potential. Going around a corner on the street so I can decide if it over- or understeers--not happening! My car will spin up the tires in first any time. It will spin them up in second in below about 50 deg. ambient temps. In the summer I just need to ease the gas in first, second is fine.
 

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I would like to know how street tires compare to the Goodyear billboard bias ply tires? Anyone run both both? I have billboards and I really think they hook up very well. I don't think I could break them loose going into second unless I really tried. They throw up more debris than the street sweeper and they tend to find grooves in the pavement. But otherwise roll smooth, handle predictably and are well balanced. I may try some street tires next, I would hope they hook up as well as the billboards, but it sounds like some tires don't.

I only have about 1700 miles so far, and haven't REALLY tested the limits, as I don't find the street a good place for that.
 

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I've been using HTR-Zs on my Mazda3 for a couple of years. I think they're great. They have amazing grip in dry and wet conditions. They have a relatively soft compound so they seem to only last about a year.

I also used a set for my Challenge car back when I was doing DE but, stupidly, I did not get them shaved. They are not a good track tire with full tread.
 

· 1st RFM/FFR Legacy Winner
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I have both Nittos in 315dr and Sumis in the 315 on a 10.5 rim no center wear.
Bob
Same size rims here. I ran the rears over inflated at 28 PSI due to a defective tire gauge for about 8,000 miles. The second set runs at 22-23 psi so I will observe the wear pattern.

Greg
 

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Jeff is right, some very broad statements being made here. There is a huge difference in the HTR-ZII and the HTR-ZIII. I run the latter. While traction is poor when these tires are cold after about 20 minutes of driving I find they soften up and stick well. Most all complaints I have heard come from the HTR-Z and HTR-ZII. As far as the tires wearing in the center there are two issues at play here: 1-too much air pressure in the tire, equal tire temp across the tire when hot will tell you you are running the proper pressure. I run 18 lbs. in the rear tires of mine. 2- spinning the rear tires is going to make the tires grow in circumference and wear the center of the tires. While I am not disappointed in the current Sumitomos I now have on the car, I will probably try a set of another brand the next time around to see if there is a measurable difference
 

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Happy with my Sumi's. Strictly steet use, not drags or autocross. As has been stated, what do you intend to do with the car.

Ralph
 
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