Tire Air Pressure
893
Member
253 days
TriSooner posted 5 weeks ago.
On clinchers, 120 sounds about right. That's what I roll on. I've never given any thought to how heat effects tire pressure. I could be wrong - I'm no thermodynamics expert - but I imagine the impact of typical summer heat and hot road contact is minimal. Are you getting a lot of blow-outs? If so, I imagine your frequent blow outs aren't from the heat but caused by tubes that aren't 'seated' properly on the rim and are getting pinched between the rim and bead of the tire.
508
Member
225 days
jsk85 posted 5 weeks ago.
I do 120psi on my clinchers...never an issue with blowouts *fingers crossed* in any weather thus far
360
Member
219 days
jhudalla posted 5 weeks ago.
120 as well. Though I've heard fools in the local bike group gloating about theirs being 160... STFW?! 120 - just do it.
Weary is the path that does not challenge.
25
Member
850 days
daveg posted 5 weeks ago.
I heard 2 blowouts right around me and passed many flat tires in the NYC Tri this past Sunday. My father said perhaps the heat from the road affected the pressure as does in stock car tires. (we understand the difference in speed here, but similar situation)
will stay at 120 as well. no problems yet...
16
Member
1184 days
kgarnier posted 5 weeks ago.
Hi.. from what I've heard and researched on it, tires will blow from the heat. Race directors around here will advise to wait and pump up your tires to desired pressure just before the start (if your pre-checking bike the day before).
If you put 120 into a tire at 50F in your cool basement, and then bring in to transition for bike check in the day before a big race, the tires could bake in the sun at 95F for the day. That 25 degree temp swing (25 K) can up your tire pressure close to 10%... so if they're rated for max pressure at 120, they could go to 132.. and even higher i imagine when you add in most tires are black (absorb every bit of heat from the sun).
I'd figure that most tires could handle some extra pressure above their rating, but depending on their wear and any nicks/abrasions in the sidewall could change that.
Mine are rated for 120, I leave them at 90-100 when I check in bike (usually the day before in 1/2 IM races) and then top them off the next morning. At least then they don't spend an afternoon baking in the sun so I can arrive at 6am the next morning to a blown apart tire.
just my .02
942
Member
1109 days
PJT posted 5 weeks ago.
1. Read the sidewall of your tire for the recommended pressure range and stay within that range.
2. If your wheels have documentation indicating a max pressure that is lower than your tire, you'll want to heed that as well. (E.g., Michelin's max pressure on pro race tires is 116 psi, but Zipp says no more than 110 for 23mm clinchers on its rims). Blowing a tire off a rim is not fun.
3. If it is raining or wet, consider shorting yourself 5 to 10 psi for added grip.
As far as ideal, for most of us on most clinchers I think between 110 (for lightweight riders) and 120 or so is generally the best way to go. Michelin publishes a chart for inflation based on rider body weight, and it says that anyone over about 175# should be at their max of 116 psi.
I'm a skeptic on the idea that heat expansion really does burst properly-mounted tires on a regular basis, but to be safe I also only fully inflate them right before the race. :)
239
Member
576 days
KitKat posted 5 weeks ago.
I pump mine up to 120psi unless I'm riding at altitude. Our coach advised us to go 5-10 below max, which put me at 110 and I was fine. We were climbing Mt. Bachelor (3500-6300ft elevation in 80+ degree heat) and I head tires popping right and left, lol, ok over dramatic there but I did hear and see 3-4 people pop while climbing.
Pain is weakness leaving the body
http://krazykitkat.blogspot.com/
751
Member
789 days
tsilcyc posted 5 weeks ago.
I've been told that tires can handle more pressure than what they state is max. It would seem to make sense because not all pumps are accurate. The number being tossed around was 30% more. I've never tried it and don't plan to either. I run 110psi in Michelin Pro Race 2 & 3's and have never had a problem filling them in the morning and racing in 105 degrees.
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1619
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995 days
133
Member
119 days
azmojo804 posted 5 weeks ago.
tri-ac wrote:
110psi for me
i'm +/- 195# and that pressure has seen me thru potholes & high temperatures
100% ditto.
I'm in AZ and have ridden at 115 degrees with 110 psi. My tires are only for max 110, but I pump to 105-110.
68
Member
319 days
vistring posted 5 weeks ago.
110 front 118 rear
I don't know the truth behind this, however here it is. If you take it up to 160 (use tubulars) then the tire will actually bounce around more, slowing you down, but it will "feel faster," unless you are on a very smooth surface.
3330
Member
1318 days
RV posted 5 weeks ago.
I know people that left their bike in the car in the sun and had tires blow.
I will take a few pounds out of the tires if I know the bike will be left out potentially in the sun for a long period.
Specifically I do this at IM - where the bike is racked the day before the race and sits there baking all day.
Don't want to arrive the next morning to have to change out a tire.
Then pump 'em back up to max as stated by the tire manufacturer for race day.
RV
It takes a long time to get good. - Scott Molina
Slow is smooth; smooth is fast. - Rich Strauss
68
Member
319 days
vistring posted 5 weeks ago.
RV wrote:
I know people that left their bike in the car in the sun and had tires blow.I will take a few pounds out of the tires if I know the bike will be left out potentially in the sun for a long period.
Specifically I do this at IM - where the bike is racked the day before the race and sits there baking all day.
Don't want to arrive the next morning to have to change out a tire.
Then pump 'em back up to max as stated by the tire manufacturer for race day.
awesome advice
88
Member
1424 days
hipfan posted 5 weeks ago.
I remember watching the pre-race on Iron Man Live for I think IMAZ (don't quote me on this), and they were showing th volunteers running around the transition changing peoples tires so that they didn't arrive to a flat.
I made a mental note that for races that it could get real warm, to leave the psi a couple pounds below 110 (max for my tires). That way they can expand in the heat. I also made a mental note to thank every volunteer possible. You never know, that person might have saved your race without you even knowing.
Cheers
I usually inflate my tires to 120psi.
When riding in the heat, how does the air pressure change?
Should I only inflate to like 115 and anticipate the air expanding?
Minimizing blowouts is the goal here right...