Those of you following my previous Sumitomo HTR Z III review posts may be wanting to hear more good things regarding this tire and it’s track-worthiness. My test car, a 99 FRC Corvette, was just sold but not before I had the chance to flog it one last time at Summit Point’s Main Circuit. It would prove to be a brake fluid boiling, serpentine belt shredding, tire smoking, rotor cracking, banging off the rev-limiter at 140 MPH type of weekend! AWESOME! And you know what would have made it even better? NOT having Sumitomo HTR Z III tires wrapped around my SSR GT2 wheels. You see where this is going.
This was my third or fourth track weekend on these tires and they’ve been heat cycled plenty more than most buyers will ever see. In Sumitomo’s defense, up until this weekend I would have said they were good enough for a bit of track use. Definitely wouldn’t set any record laps but they would be fine for the occasional HPDE.
My first gripe with the tires is that the sidewalls are way too flimsy. What this means on track is that the car doesn’t respond quickly to steering inputs. On the streets up until the first track day it wasn’t very noticeable on the streets. After that first day back on track in the Virginia heat the sidewalls seemed to throw in the towel. Now they bend over like there’s money on the ground.
Okay. It wasn’t that bad but something most performance oriented drivers would notice. Adjusting the tire pressure didn’t seem to help much. After 20 minutes on track tire pressure would increase from 35 PSI to around 42. The tires were wearing right up to the indicators on the sidewall.
Perhaps the worst characteristic of the Sumitomo HTR Z III is braking performance. Using Performance Friction Z-Rated pads I was able to engage ABS with minimal pedal pressure. The tires were also quite vocal. Like a pig on it’s way to the slaughter house, I thought I heard them squealing before I even got in the brake zone.
So I’ve covered the sidewalls and the braking performance. What else? Well, that’s probably about it, honestly. Dry traction was good. To recap, I feel if you’re only going to track your car once or twice a year, and it’s not a 3500 lb heavy weight, then you’ll probably be fine. If you’re a cheap ass who buys nothing but economy tires then it’s probably not much different to the performance you’re accustom. If you’re coming from the Yokohama AD07 then you’re gonna be regretting the decision big time.
All in all, I have nothing bad to say about these tires on the street other than wet braking performance could be much improved. If you’re on a budget then Sumitomo HTR Z III deserves a look. They’re not bad tires at all but I wouldn’t recommend them at all for use on the track. The Sumitomo HTR Z III tires may please your wallet but me mindful of the trade-off.
great writeup. I bought these tires a couple months ago based on your and Tire Rack’s reviews. Overall, they are great on the street, but as you found, just don’t hold up on the track I have, as you say, a big heavy pig…a mostly stock 2005 G35 sedan 6spd. I have sway bars which make the car wonderfully neutral in the turns and had put in track brake fluid and pads.
It was a single day event at Motorsport Ranch. 3 morning sessions and 3 in the afternoon. By the 5th and 6th sessions I definitely wasn’t as happy with them. I’m not sure if I was getting sidewall flex, but they definitely got a little greasy on me. The configuration we ran was counter-clockwise, so the right tires got a bit more of a workout. What dissapointed me was my front right tire started chunking a bit at the end of the day. Nothing major, but annoying nonetheless.
So I fully agree with your review. Great if you’re on a budget…which I am, so I’m not terribly dissapointed as I may not make it to the track again for quite a while. On a lighter car, who knows, these tires possibly are quite amazing.
Any thoughts on the BF Goodrich G-Force T/A KDW’s? They seem to have similar performance characteristics and are at a similar price-point. I wonder how well they hold up on the track.
BFG has a KDW and KDW 2, I wouldn’t doubt that either of them out performs the HTR ZIII on track. On a heavier car like your G35S I’d suggest a tire with a stiffer sidewall such as the Falken RT-615 and a pair of well engineered front camber arms(Cusco or SPL).