dr_max

This is the second time it happens to me this season.
I go for a ride, has to ride on the shoulder of the road on heavy traffic roads for couple of kms with some gravel rocks on the shoulder and the first time my front tire was slashed on the side of the rolling band. Didn’t notice it and the tire blew out when I pumped it to 110 PSI and saw that after I inspected the tire.

now it happened Sunday on the road my rear tire blew out and had to repair it and squeeze a Lezyne boot temporarily to get back home.

never ever had that problem with 25cc and I have been riding those for decades.

is it the 28cc that makes the lateral part of the tire prone to that?

WhyFi

Sounds like you were lucky in the past - GP4Ks have a long history of sidewall slashes.

popeye

28C 110 lbs? What do you weight? It is the supple sidewalls that make these great riding tires.

Ogsarg

I gave up on the GP4000's for that very reason. Had several sidewall flats and one blowout (lost all pressure in about 2 seconds) from hitting small rocks and general roadside debris. I am trying a GP5000 on my new bike rear and so far so good but only have about 500 miles on it.

Why are you running 110PSI? Unless you are a really big guy, that is way too high.

Elvo

110 is really high for 28mm

sfrider 

Definitely not a gravel tire. I do occasionally ride dirt shortcuts or short byways for the scenery, but if it gets rocky I step off and walk it. Fortunately in my case rocks are easily spotted well in advance, and typically easily avoided. But if there's no getting around... I'll walk a few paces. But even then I understand doing this will likely shorten their life span. (This is GP5k though, but I rode 4000s before, and 3000s before that, and they're all the same deal.)

smashndash

It’s worth noting that higher pressure tires will cut more easily than lower pressure tires.

If you weigh 160-180lbs, try going way, way, way down. Like 75psi. See what happens.

Tacoenthusiast

It's really high for 23mm

It's really really really high for 28s

Nachoman

I stopped buying them for this reason too.

mprince

I have these in 25mm, I am far heavier than you and keep pressures in the 90's, I've ridden them as low as 80-85 with no issues. Mine are fairly new, but no sidewall issues yet, and I have been checking them pretty regularly.

TMonk

I've had sidewall slashes on a few GP4k's. In all other regards they're a decent tire so I'll buy them and risk it if they're heavily discounted. But otherwise no.

MSchott

And I’m 200 pounds and am riding these tires in 23mm width at 80-85 psi with no issues.

79pmooney

I ride Vittoria Corsa G+, 25s @ 102psi, 28s @ 92psi. I don't ride gravel anymore (too rough on my too-many-times scrambled brain and when I knew I was going to be riding gravel, switched wheels and tires but if the pavement ends, it would never occur ot me to walk. I have cut the G+ tires, but not often enough to address as a worry.

I'm not a good judge of Continental tires. Other than the ice tires I love (for one weekend a year here in Oregon) I have had nothing but poor experiences on Contis.

Ben

BlazingPedals

Depends on rider weight. I run 23s and at 100psi I'll get constant pinch flats, sometimes several on a single ride.

dr_max

I had a snakebite pinch flat once at the end of last season hitting a pothole with my 28cc at 90psi in my rear wheel.

thats the only reason I run them at 110 now,
I’m 170 pounds off racing, 145 pound while racing

smashndash

You may as well switch to solid rubber tires with that logic. The tires exist to deform to the road. You should go TL if you are that afraid of pinch flats.

I weigh 145lbs at my heaviest and I ran 45-50psi in my 28mm tires, with tubes. I can probably count on one hand how many times I’ve pinched. And some of those were totally brutal hits.

I’m not gonna command you to run lower pressures because everyone is allowed to have their own opinions and you’re not hurting anyone but yourself.

However, you’re not the only person to ever encounter a pothole and perhaps you should consider why the rest of us don’t just run the max pressure all the time.

Leinster

Similar here. I’ve taken them off road, hit potholes, no issues. I may be tempting fate here...

dr_max

have you read studies on the lowest rolling resistance according to the tire diameter?
I give more weight to that than personal opinions or internet experts.

WhyFi

We have. Have you read studies on suspension losses?

billridesbikes

Not going to enter the tire psi debate but riding where the road derbies have accumulated only leads to tears and heartache.

Not only is it strewn with trash and debris but gravel can hide sharp road edges or shallow depressions filled with sand and gravel. Drivers treat objects in the gutter of the road, including cyclists and pedestrians, with complete disregard as if they are blind to this part of the road. It’s better to ride out to the left just a bit away from the debris, ideally a few inches to the right of the fog line, even on a very busy road so you have some visibility and don’t risk damaging your tires or sliding out into the road because a gravel patch takes out your front wheel.

If there is no way to avoid riding in the gutter then switch a tire that can take this kind of abuse like Gatorskins, and save the lightweight tires for race day or events.

dr_max

“

Tyre pressure and rolling resistance

“It is true that the higher the inflation pressure, the lower the rolling resistance of the tyre,” Schwalbe UK’s Dave Taylor says. “It’s also worth pointing out that a tyre’s susceptibility to punctures is lower with high pressures, too. And if the inflation pressure is continuously too low, premature tyre wear is the result, which usually means cracking of the sidewall and unnecessarily high abrasion.””

dr_max

““If you have great road conditions and you would like to ride very fast — in a race, for example — inflate to the maximum permitted pressure. Using the example of a 25c tyre, you can reduce rolling resistance by around 10 per cent simply by using 8.5 bar [123psi] instead of 6.5 bar [94psi].””

it’s not even a debate

smashndash

Again, you should ask yourself why we don’t ride on solid rubber or rubber coated steel tires. A steel tire would easily record fewer losses than even a TT tire pumped up to 150 psi. But we don’t use them.

Your excessive sidewall cuts are a) to be expected from the gp 4k but also b) to be expected from a tire run at excessive pressure.

https://www.cxmagazine.com/gravel-ti...all-protection

dr_max

lower pressure is worse, it is exposing more sidewalls to the cuts.
as stated in your article

““lower pressures expose more sidewall to cuts. Trends towards wider rims are exposing more tire sidewalls to rocks too, sometimes before the sideknobs would hit. This is a big reason why our gravel tires either have sidewall protection via EXO inserts or bead-to-bead protection via our Silkshield breaker.”
Brown did add that “[l]ower pressures may [also] bottom out on the rim, pinch flatting the tube or tire casing, but higher pressures do not add protection against cuts. Lower pressures will, however, expose more of the sidewall to gravel by flattening out the tread,” before making sure to note that Maxxis’ “Mud Wrestler CX tire also has EXO sidewalls since you never know what you’ll run into in a deep enough mud-hole.” Interesting, and a good note of caution.”

dr_max

land the reason we don’t ride in solid rubber or steel tires is for optimal weight/resistance scenario which is best in inflated tires with lower inertia to accelerate and climb hills with a trade off being prone to puncture.

same reason they use carbon frames, the stiffest for the weight, even if they are not the most durable or stiff.

some people would prefer riding stainless steel frames with steel wheels at 15kph and never change parts.
come people would prefer riding carbon frames with rubber inflated tires and change tires during the season.