I have a few questions about tire pressure. I have been racing in an armature racing league for years for a hobby. I now reside in Taiwan and have been racing Honda NSR’s for a few years. The climate in Taiwan varies dramatically from summer to winter. During the summer it is scorching hot and during the winter is it actually very cold. It is humid all year round. Our season runs all year long. I run slicks without tire warmers on my NSR 150cc. I have found that running 26psi cold works well all year around. My questions are, should I be using a different psi setting for summer compared to winter? I have never heard this theory, but one of the spectators that comes to the track said that I need to be running high psi for hot days. Isn’t that the complete opposite from what I should be doing? He swears that it is true. I’m skeptical. I hope some of your fellow racers can give me some advice. Thanks.
Measure your tire pressure after doing a couple of laps when running 26 psi. I don't understand why you should be running high psi for hot days?
Yeah I dont understand that either! It was just what a spectator told me. What psi are you guys running when racing?
Guessing he's talking about cold pressure, as the tires won't gain as much heat on-track on colder days.
Wouldn't you want a little less pressure on cold days? Help the tires get up to temp better and prevent cold tearing?
Well either one just to see by how many PSI the tire pressure inscreases. Did the spectator say why he swears you should run high PSI on hot days?
He is a "magazine reader" doesnt have any track experience. He said he read it. I have been racing cars and motorcycles since I was 16 years old. I didn't argue with him, but from my personal experience I find that if I have too much air in my tires on a hot day, then my tires slip. It got me thinking though, and was wondering what other racers are doing expecially when the climate here in Taiwan is so unstable.
I would suspect that higher pressure in hot days would help with less tire flex and run slightly cooler... Compared to lower PSI because you expect the high track temperature to raise the PSI in the tire... If it's hot and you lower the PSI the tire would over heat form excess tire carcass flex... To me it makes sense to go a couple PSI more when it is hot... I live in Arizona and here our tracks get to 130+ degrees... Lowering PSI gets the tires really hot riders start slipping and sliding more... I would expect to run lower PSI in cold days so tires flex more, stay heated by the flex of the tire carcass and offer a slightly larger contact patch... We are only talking 2 to 3 PSI total from cold to hot... NOT + 2 to 3 PSI from normal on hot season... And -2 to -3 PSI from normal on cool season... Luis
I'm actually from Arizona, born and raised! Did you ever get to ride Arizona Motorsports Park? It eventually got closed down and now I haven't heard about it since living in Taiwan. Anyway, so when the track is 130 degrees what is your psi at cold, or with tire warmers on? Like I said, I usually go out with about 26psi cold, but I feel that if it is scorching hot outside and i have too much air in than I feel my tire doesnt grip as well. I am only talking about a +2 or -2 psi difference. Doesnt the hot weather affect tire pressure by a few psi?
I would really like to hear from guys that are running race compounds. I really want to play with my psi a bit. What is a good starting point for psi cold? Like I said I run 26 cold. I have a race this weekend, so I will be practicing and checking my psi when my tires are hot. It will probably be a hot race this weekend. Should I be have slightly more psi in my front tire than the rear and why or why not? What psi should I see when my tires are hot?
The Arizona Motorsport Track is starting to open up... But not for profit... So there are no schedule track days... However, we have Inde Motorsports Ranch in Wilcox, AZ... Well worth the drive!!! I have warmers, so I set my PSI with warmers on for at least 50 minutes... Pirelli Diablo Supercorsa SC2 - 32 Front HOT 29 Rear HOT... Michelin Power One - 29 front COLD, 21 Rear COLD... The tires will get hotter on the track, but at that point PSI is not relevant... Set tires PSI on warmers (HOT) and you will have consistency... Unless you are within 3-5 seconds of track record lap, I would follow manufacturer recommendation... So far, I do not know what tire brand, model, compound or date of manufacture you are using, to recommend any specific PSI... Regards, Luis PS: Here is Inde... http://www.youtube.com/v/l_NKOH49S78&feature=player_profilepage
It entirely depends on what brand and model of tire you are running and what the conditions are, you might want to include that information. I run NTECs and I set them to 30-29f/21-20r cold
I am using Bridgestone YCX slicks (Soft compound.) Our track isn't very long, only about 1.5 kilometers. When we race, we only race for 13 laps. I don't know if that info helps. I am reading so many difference conflicting theories on the Internet. I did find a magazine article that says for track days start out at 28-34psi cold. If it is around 60 degrees than start at the low end. It it is about 80 degrees or higher than start out at the high end. Then go out for a 20 min session, come in and feel your tires. If they are only mildly warm than drop the pressure by 1 or 2 psi, if they are scorching hot and the edges are bluish in color that means they go too hot and add 1 or 2 psi to them. I would think starting out at 34 psi on a hot day would just be too much air. I also notice a lot of guys are running a little less in the rear than the front tire. Why? I have pretty much always ran the same amount. I see many of the RS 125 guys on the forum boards are running around 25-28 psi cold. 34 cold just seems way too high! I don't have tire warmers. There aren't any racers out there using them either. We have to bring out bikes into the pitts about 25 min before the race anyway and there isn't any electricity there. So I would think tire warmers wouldn't give me any kind of advantage for the race. We also get 2 warm up laps. I think they would help for practice days though.
We usually buy warmers and a power generator to run them... I been to Races in Mexico and Central America... They do not see the cost vs. value of owning tire warmers... The rear tires get less PSI because usually they are bigger than the fronts, carry more air volume and are the driving tire... Less PSI provides slightly larger contact patch, grip and traction... I agree 34 PSI COLD seems like a lot... If the RS125 guys are using 25-28 PSI you can experiment within those parameters, and determinate what is working by feel and by tire wear... Excessive tire wear may be due too low PSI.. Luis
