S.A.S.C.
Solo => Technical Talk => Topic started by: MurrayPeterson on May 11, 2015, 08:09:44 AM
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Jo and I drove up to Edmonton for an evening autox, and we went on our new RE-71R rubber (225/50R116 on all 4 corners)
First off, I have to say that these tires are very nice for street and highway driving. No tramlining like the Dunlops, and much quieter on the highway. Jo and I could hear each other without needing to shout; the Dunlops required a pretty good bellow to be heard. The 71Rs don't have the tread block drone of the Dunlops, just a hissing sound.
Autox was more of a mixed bag. The grip is definitely great (better than the Dunlops), but I had a few other issues with them. The feedback to the wheel isn't nearly as precise as the Dunlops (softer sidewalls). And I was getting some very strange behaviour when they started losing grip. They would start squealing and sliding, and then go silent and grip again. Very disconcerting, and not something that inspired confidence. As a result, I never managed to get the best out of these tires.
I need to play with pressures next weekend to see if they have a different happy place than the Dunlops.
Oh, tire wear. 600 km of highway driving, and autox runs (around 70 seconds each). Fronts had little wear -- perhaps .1 mm. Rears lost about .5 mm. Probably good for a dozen autox events, but highway travel is going to be the limiting factor, since that is what wears away my rear tires. No launches at the autox (worried about clutch), so the rears weren't spun at all.
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Thanks for sharing Murray, I was wondering how they might compared to the ZII's
After I burn off my current set (I honestly don't expect them to make it much past the school later this month) I am going to try going up to a 50 profile of this tire.
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Update from this weekend.
The tires love the cold and wet. Saturday was cold, rainy, and miserable, but the tires handled all of this happily.
My weird experience with the grip loss at Castrol was not repeated at the Westerner. Perhaps I was feeling the effects of the road crown at Castrol? Anyway, they were well behaved on Sunday. I did need to run higher pressures than the Dunlops (39 front, 38 rear) to prevent excessive rollover.
Summary to date:
Soft and quiet ride on the highway (compared to the Dunlops)
Very high grip levels
A bit softer and less "crisp" than the Dunlops, but not something that can't be dealt with by applying my inputs a bit sooner.
Higher wear rate than the Dunlops. I'll measure them today and see how much rubber is left after 2 events.
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Tire wear as of this morning: a bit less than 7/32 left. Wear at the Westerner was almost entirely on the front wheels; even the tire spinning launches didn't make too much of a difference in the rears.
Looks like these should be good for about 8 events when Fort Macleod is added into the mix.
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Played around with tire pressure some more this weekend. These tires really don't seem to care about pressure -- I went from 37 PSI up to 49 PSI, and the grip didn't really drop off until I approached 50 PSI. I think I will run at 39 front and 37 rear; higher than the Dunlops (37/35), but these tires need more pressure to prevent excessive rollover.
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I was experiencing the same thing with them, despite the heavy sidewall I find I have to run higher pressures in them than other tires
I still don't know exactly what I should be running to optimize them
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The tires are now down past the wear bars at 2/32 inch (center, rear tires). The edges are showing a bit more wear (probably another 1/32 inch).
72 dry runs, 11 wet runs, 3400 highway kilometers
I think they are good for one more event, but no more. Let's call it 100 runs.
In comparison, my Dunlop Star Specs were good for 200-250 runs. It appears that the Bridgestones have about %50 of that lifetime. Acceptable, but not thrilling :(