BRIDGESTONE R10 DOT RACE TIRE TEST Part 2
To order this tire online, go to: http://viets-performance.com
- rear tire 190/55 x 17 Type 3 medium compound
- front tire 120/70 x 17 TYPE 3
AMBIENT 98 degrees F
TEST BIKE 2009 R1
Having achieved optimal tire wear in the original test by tuning chassis and suspension using Bridgestone’s recommended hot pressures, it was time to experiment with tire pressure changes only. I had mentioned that the right side of the tires were balling up more than normal, (those are slow survival type corners requiring maintenance throttle or only slight acceleration) and that normally means tire pressure is too low creating accelerated wear.
In addition my initial response was that this new R10 was very close in construction (therefore feel) to the Pirelli race DOT. For my own personal tastes, I like a tire to hold its shape under hard acceleration and heavy braking so I go far beyond recommended pressures until I find what I need. In the case of Pirelli’s I ran 38 hot in the front and 34 hot in the rear on my VFR400 at race events.
Remember that in testing you need to find both bad ends of the spectrum and then move in on the target zone!
For session 1
- hot tire pressures after 30 minutes on the warmers were set at 40 hot front, 38 hot rear. The tires amplified all bumps, even the smallest ones and the tires suffered from deflection over high speed bumps. While the bike could be ridden the risk of deflection and potential low side or high side was too elevated, therefore I could not be aggressive with the brakes or throttle.
Note much less balling up of tire rubber on the right side.
- after 4 laps I came in and reduced the pressure to 38 front and 35 rear. All bumps were less noticeable and the roll profile of the tire was very solid with very little sidewall flex very nice. A much more comfortable feeling and throttle roll ons and trail braking were much more pronounced and aggressive.
- three laps later pressure was reduced to 36 front and 33 rear. Sidewall flex became easy to recognize as did the change in roll from side to side much slower on the transitions and less steering under very hard trail braking. Not what I was looking for therefore in a few laps I had gone from bad to bad.
Before session 2 could start, the tires had to cool off as much as possible in the shade for 40 minutes. The tires were over filled with air and put on the warmers for 30 minutes and then set at 38 front and 35 rear before immediately heading out onto the track. The goal was to put consume a full tank of gas on track (45 minutes) and set a pace that was reasonable for that amount of time on the bike at 2:03 which would be the top of A group at this track.
The roll profile of the tire was very firm allowing very quick transitions side to side. Under very heavy trail braking, the bumps were more pronounced but there was no deflection, so corner entry was much more precise. I could not feel the side wall flex much on flat or off camber turns, but at full load on up hill trail braking corners I could feel the sidewall start to change shape which altered the steering input. As this was only experienced in 2 turns at this track, that was a fair trade in my book.
Mid corner the tires felt much more planted as did the bike with feedback coming through the bars rather than being completely absorbed by the tires. The added bonus was that mid corner corrections were much more precise and happened quicker. That brought up my mid corner speed overall and allowed me to feel much more relaxed in changing lines based on working my way through traffic.
On corner exit, the sidewall held firm in all but the hardest accelerating corners. In those turns it felt like more of a drift than flex, and that was verified in turn 6 and 8 where you go to full throttle quickly. So, there’s a potential further test of going one pound lower in the rear to see if grip returns as drifting serves no purpose other than for fun!
All in all psychologically a much better session with full confidence in the tires especially the front, so much so that the Klucky Pucks happily started smoking very heavily again Isn’t life grand!
Image courtesy of Joe from 4 The Riders.
Manufacturers have to put out a starting point for tire pressures, so you are given that information. That doesn’t take into account ambient and track temperature, your lap time speeds and ability, your riding style and the compound you are using. You cannot just put tires on a bike any more, you have to be very selective what you choose based on the type of use you are putting the tires through.
Street, track or race you must take the time to make appropriate geometry and suspension changes to accommodate the tire carcass and compound, and there’s no short cut to that process, even for people like me that do this every day. Tires are very expensive when you get into track/race use, so we need to get the best out of them.
With a well set up chassis and suspension, that is a balancing act between grip and longevity based on pressures.
ARE THESE TIRES REVERSIBLE?
Racers know which tires can run in either direction and which cannot. DO NOT under any circumstances guess. From testing the answer is no with the R10 – it is directional so make sure when you pick your wheels up the arrow is facing the right way.