ive had my sumi's on for about 10k miles. still holding up well. a lot of tread life left. awesome tire for an awesome price.

 

[QUOTE=oldtrlrnr,Jul 16 2009, 03:21 PM]I'm curious about the effects of 225/45-17 & 255/40-17 on acceleration as well as handling.

 

the key to our cars is tread width and looking at your 225/245 set-up with the sumis your tread width is 225/8.1" 245/8.3" = massive oversteer.



HTRZ-3 215/45-7.4" 245/40-8.3"

OEM RE050 215/45-6.7" 245/40-9.1"

CR/RE070 215/45-7.4" 255/45-9.1"

HTRZ-3 215/45-7.6" 255/40-9.1"

HTRZ-3 225/45-8.1" 255/40-9.1"

the stagger ratio is clsoer with 215/255

http://www.tirerack.com/tires/Spec.jsp?mak...tirePageLocQty=

 

[QUOTE=TRDLiquidSilver,Jul 17 2009, 04:06 PM] the key to our cars is tread width and looking at your 225/245 set-up with the sumis your tread width is 225/8.1" 245/8.3" = massive oversteer.



[B]HTRZ-3 215/45-7.4" 245/40-8.3"

OEM RE050 215/45-6.7" 245/40-9.1"

CR/RE070 215/45-7.4" 255/45-9.1"

HTRZ-3

 

[QUOTE=CaptainMike,Jul 17 2009, 10:03 AM] What are your alignment specs, specifically camber and toe?

 

I've had these tires on now for about 2.5k miles including a trip to Wake the Dragon in April. They were brand new for the trip to the Dragon and they were broken in by the time of my arrival. They handled well for this Dragon noob, though I did notice a little sidewall flex in the steepest turns. They are excellent cruising tires even on my 18's. I drove them in rain only once--on the way back home after having them installed as I don't take this car out on rainy days. They pretty well as I would expect for brand new tires.

My specs are listed earlier in the thread but I'm running 225/255.

 

I have the 215/255 htrz3 on ap2v1's lowered about 3 inches, no finger gap at all and have never had an issue with rubbing and never rolled fenders..

 

I got the Sumis with about 16,000 miles on my '05 AP2. The old OEM RE050 performed very well, but for the last 1,000 miles or so, I started to get pulsing vibrations which was bad enough to make my left mirror nearly unusable at night. Based on the wear pattern, it appears that the rear left tire was the culprit. There was slightly uneven wear on that tire with about 2mm on the left groove and 4mm on the right. A week prior to buying the Sumis, I balanced all 4 wheels, which didn't eliminate the vibration, so I am positive that the cause was due to uneven wear in the rear left tire. Rear right tire had an even 4mm of tread and the front two had 7mm of tread left. Given the vibration issue, I just swapped out all 4 since I wasn't sure what was causing it until the vibrations went away with the new tires.

As for the Sumis, I bought 225/255. My ultimate judgment is at the bottom of this post, but here are some contrasting observations after driving on the Sumis for 600 miles.

1. Noise - Much quieter. I can talk on a cell phone at 75mph now, whereas it was nearly impossible to have a conversation with the RE050s. The volume difference is also noticeable when I come to a complete stop with the top down on a quiet stretch of road.

2. Wet Grip - It is much better, but I don't think my memory is good enough to compare since I was moving from nearly worn tires to brand new tires with full tread depth.

3. Highway sweepers - I drive every day on a parkway with nice sweepers that most commuters take between 55 to 65 mph. Sometimes I drive a *little* faster. They have signs recommending 45 mph. What I liked about the old RE050 was the instant set as I turned the wheels about 15 degrees, which some people have described as go-kart like handling. With the Sumis, my confidence is slightly lower. There is a definite roll before the tires set and I need to adjust my wheel mid-turn more than what I needed to do on the RE050. Said another way, I'm not sure if the tire "sets" the way the Bridgestones did and feels mushy. I still can't quite tell if the issue is soft sidewalls or grease during the break-in period. If people are interested, I can report back in another 1,000 miles next month. (On a side note, my pet peeve is anyone that describes any road car as go-kart-like, especially if those words are used by professional auto journalists. I bought the S2000 b/c I got into go-kart racing and wanted something most like a go-kart for the road. And of course the S2K doesn't drive like a go-kart. Nothing road-legal drives anything like a go-kart, which is a toy that lets you drive 11/10th all the time at 2.5 Gs with no moving suspension bits).

4. Rapid left/right - Near my home, there is an uphill road that is very narrow and tight. It requires rapid left/right turns (maybe 20 turns in about a mile) which most people take around 30mph. It's not as tight as an autocross route, but it is definitely tighter than most canyon runs on the West Coast or the Pacific Coast Highway. I safely take these turns at 45 and have gone faster before. Despite what I said in 3 above, I don't notice the difference as much on these rapid turns with the Sumis. My theory is that in a high speed sweeper, there is one input and a sustained input, which calls out the softness in the tires more. When I'm rapidly changing directions and when the car is not given enough time to find a constant set, it can "hide" the softness in the Sumi tires. I wonder if that is the reason why some of the auto-x'ers on this forum find the Sumis acceptable.

5. Cruising comfort - Highway driving is noticeably more comfortable with the Sumis.

6. Look - 225 nicely fills the wheel-well. I think I personally like the sharper edge of the Bridgestone better than the softer rounded edge of the Sumis. I know some of you guys care about every detail, but to be honest, after a couple of days, I don't really look at the tires that much.

7. Jim at TireRack - After reading about him all over S2Ki, I called him up. He was very nice and very knowledgeable. His price was the same as what you can get on your own on the website.

8. Steering weight - 225s made the steering wheel feel heavier.

9. Road feel: I never thought that the steering wheel in the S2K provided a lot of road information. The chassis provides more information in my opinion. The road feel is slightly dulled in the Sumis.

Verdict: I am not ashamed to say that at nearly 40 years of age, using the S2K as a DD is not always fun. With the Sumis, there is enough change in the character of the car to be noticeable. It is easier to live with and dare I say, comfortable. That said, I have a minivan (or my wife's G37) to drive if I want more comfort/luxury. I bought the S2000 for sports car handling. I read some people argue that Sumis deliver 95% of the performance of tires that cost twice as much. I disagree with what that 95% means. If people are saying that the difference in lateral grip is about 5% lower, I agree. However, even the cheapest set of tires will offer 90% of the grip offered by the Bridgestones as measured by lateral acceleration Gs. So the spectrum of grip is 90% to 100%. If the entire range has a delta of 10%, than a 5% degradation really means that Sumis offer 50% less performance than the best tires. I don't think anyone can say one tire is better than other. If you want to commute in the S2K and found it to be harsh, I recommend the Sumitomo HTR Z III. If you care about performance, even if you only drive on the public roads, I would say that you will notice the degradation in performance even at less than 10/10ths. I personally wished for more comfort and got what I expected. The difference in performance was a little more than what I expected. I will enjoy the comfort for now, but my next set will be a more aggressive compound and I am willing to sacrifice comfort and cash to get it.

 

Great review and I agree with much of what you say. The Sumis are a great cruising tire. The handling will sharpen up after break-in, which for me was a drive to the Dragon earlier this year for WTD.

I do agree that for 8/10 and above driving, you need S02s (I've got an AP1), RE050s, or Star Specs.

For the record, I've put about another 500 miles on my Sumis since my last post a few above.

 

ok guys, need help here. I have 17 in CE28s.

I am leaving the original front tires on, about 75% thread life on em (federal tires)

now for the read, the Federals are 245, 40, 17. Should I go with the same size with these Sumis or with 255?