# Anyone run a 23C up front and a 25C in the back?



## MCF (Oct 12, 2006)

Just curious. I am currently running 23C front and back. Mainly because my 3T Funda Pro fork has pretty tight clearance and a 25C will slightly touch the fork if the tire is not perfect. Thinking of maybe putting a 25C on the back and leaving the 23C up front.


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## Blue CheeseHead (Jul 14, 2008)

I have considered the same thing and see nothing wrong with it. 

Continental makes the Attack/Force tire set that is front/back specific with 22c up front and 24c for the rear.

The biggest drawback would be the inabilty to rotate your front tire to the back as your rear tire wears out.


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## ctracer01 (Jan 5, 2006)

I ran the Attack/Force set last year. I think it's a great set, but as mentioned, there's no rotating. As such, I could only recommend relegating to race day only tires, as the rear wears fairly fast. And due to that, i would personally buy something else. vittorias/veloflexs, etc.

that said, running different tires does have advantages, and if you're willing to fork over a little extra cash for the 2 for 1 rear tire/front tire combo, then go for it.


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## MCF (Oct 12, 2006)

I am about 200lbs so I am thinking 25C back 23C front would be a good set up for me. Currently running about 105-110psig in the back and about 100-105psig in the front tire.

What do you mean by 2 for 1 rear tire/front tire combo?


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## ctracer01 (Jan 5, 2006)

just that you'll be buying more rear tires than front tires.

i rode 25c's all winter, and the ride quality is definitely apparent. enjoy!


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## MR_GRUMPY (Aug 21, 2002)

I use a 23 front, 25 rear, on my solo training wheelset. 36 spokes all-around.
Indestructible.


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## teleguy57 (Apr 23, 2006)

Yup, 23 fr/25 rear, Rubino Pros both. I had been running 25/25, but changed to an Alpha Q fork and found out the 25 rubbed the underside of the fork crown just enough that I had to size back to the 23s I was running originally.

I'd do 25/25 if I could, but don't really think I cna tell the difference with a 23 up front.


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## MCF (Oct 12, 2006)

Thanks...I guess I put the horse before the cart - what is advantage of running 25C in back? More comfort but a little slower? Going from a 23C at 110psig, what would be a good pressure for a 25C (again, I am about 195-200lbs).


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## ctracer01 (Jan 5, 2006)

you'll have more volume=smoother ride. not necessarily slower either.

as far as pressure, i tend to ride identical pressures on my attack force set. so i'd try 105 both ends and then adjust from there.


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## MCF (Oct 12, 2006)

Thanks! I have two 23C Rubino Pros on now and the rear one is showing a little too much wear for me so it looks like I be trying a 25C Rubino Pro on my Cervelo RS soon.

But for now with my current 23C tires, is 105psig considered high for my 195lb-200lb weight? Could I drop it down to 100 rear / 90 front or am I risking flats?


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## cmg (Oct 27, 2004)

currently running 23 conti supersonic on the front and 25 Vittoria diamante pro light on the rear with light tubes. it did take some of the buzz off the cannondale six 13 i'm running them on. But i didn't reduce tire pressure. i like the setup, seems to cruise better. does it have lower rolling resitance as the claims? who knows, i'm hoping for better pinch flat performance and better mileage. since the diamante didn't gain much weight in the 25 it doesn't effect spin up. nothing negative.


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## jmlapoint (Sep 4, 2008)

Works great.
Ran 23/25 for a year and loved it.
Only reason I changed was I had a stock of 23's.


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## giro_man (Oct 29, 2003)

I just installed the size 700x25 Vittoria Rubino Pro III on my Cervelo RS with 3T Pro Funda fork. There is no problem with the front tire rubbing the fork. The problem will occur with some other brand of tires such as Continental GP 4000. The GP 4000 tire stands taller than the Vittoria Rubino Pro (and also the Vittoria Corsa Evo). Also, my Cervelo RS came with 700x25 Vittoria Diamante Pro Light tires on both front and rear.

The advantage of a 700x25 rear tire versus 700x23 is that lower tire pressure can be used without encountering pinch flats. The larger volume tire with lower tire pressure than the 700x23 can absorb more road shock and enhance the comfort of the ride. Enhancement of ride comfort is also the reason that some cyclists use the 700x25 tire on the front in place of 700x23.

The 700x25 tire will not be more durable or longer lasting than the corresponding 700x23 tire if they are built with the same compound and puncture protection. As the rear tire carries more weight relative to the front tire, the rear tire will wear quicker. This is particularly evident for heavy cyclists. A strategy some cyclists use is to buy tires in 3's rather than in 2's as the rear tire will be replaced long before there is a need to replace the front tire.


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## fallzboater (Feb 16, 2003)

I've run 23/25 for years, and can usually use two rear tires for one front. It makes sense when you figure that you may have 60% of your weight on the rear tire (especially bigger riders), and it should wear a little longer. Running a 25 up front is a fine idea, too, but you do save a few grams with a 23. 

I'm currently using Schwalbe Ultremo DDs, which I've had a couple of casing issues with, but have worn pretty well. This week I'll be picking up a Hutchinson Fusion 2 front and Intensive rear, to try tubeless.


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## Hank Stamper (Sep 9, 2009)

At 200 pounds I think it's a good idea compared to front/rear 23s.
Compared to front/rear 25s? Not sure. Realistically if you have a 23 or 25 up front probably won't make a significant difference either way so it might make more sense to keep it simple and just use two 25's.

You already have 23s right? So just go out and buy two 25s and see what you like best. Either you'll use both the 25s or have your replacement rear tire in advance.


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## MCF (Oct 12, 2006)

Wow....these tire manufacturers make it hard. Anyone know the difference between the Rubino Pro I, II, and III?


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## cyclust (Sep 8, 2004)

Running a larger tire in the back is something everyone should do, IMO. The rear has more weight on it, so it should have a larger tire. Have you noticed that on most pre-built wheelset these days, there are more spokes on the rear? Same principal. I've run a 25/23 combo for the better part of 20 years, and have always wondered why more people don't. The Conti Force/Attack combo is a great ideal, although the tire sizes are only slightly different. I wish more manufacturers would offer front/rear sets that cater to the different needs of a front or rear tire. A little more grip on the front tread, along with more sidewall tread, and perhaps a thicker tread and tougher casing on the rear.


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## eddie m (Jul 6, 2002)

I do just the opposite. Running a bigger tire in the rear at lower pressure makes the bike feel a little sluggish to me, and not that much more comfortable. OTOH a bigger, lower pressure front is way more comfortable on my hands (which is a real issue for me) without making me slower at all. That's the way all BMX bikes are set up, and I think it makes a lot of sense for road bikes as well.

em


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## tlc4bikes (Dec 31, 2009)

I run same size front/rear on all my wheels (tire rotation is a good thing). Having not raced in 7+ yrs (raced from 1983-2002) my weight is up but at 5'10" and 160 lbs I am still (IMHO) lite enough to use 21/22/23mm tires. Road conditions/experience/comfort/rider weight/rim size/personal choice and a few other reasons effect the size of tire that a rider uses. On a side note - why do people put a "c" after the tire size? Tire width is measured in millimeters. Back in the day the French system of measuring a rim - say 700c - meant using a "c" wide tire. The French used a A thru D method of measurement for tire size. The ISO method of measurement is now enforced and the "c" for a tire measurement doesn't apply. All the 700c rims(ISO 622mm rim) that are being manufactured today will fit a wide range of tire sizes (measured in mm). So simply saying 21 or 23 or 25 etc. will address the tire width since under the current ISO measurement system "c" refers to a rim width not tire width.


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## pigpen (Sep 28, 2005)

eddie m said:


> I do just the opposite. Running a bigger tire in the rear at lower pressure makes the bike feel a little sluggish to me, and not that much more comfortable. OTOH a bigger, lower pressure front is way more comfortable on my hands (which is a real issue for me) without making me slower at all. That's the way all BMX bikes are set up, and I think it makes a lot of sense for road bikes as well.
> 
> em



me too.
Not just BMX but old school MTB also.
I was running 25/25 until I have got a gash on a supported century. All they had was a 23.
Slapped that sucker on (the rear) I have been too lazy to change it out. Won't until it wears out either.


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## abcfob (Dec 21, 2009)

I don't know how important this is in road cycling, but in general (mountain bikes and in cars), a wider rear tire compared to front will give more tendency for understeer, where your bike won't turn as much as your steering angle would indicate.

Perhaps this is not an issue in road biking, but its quite dangerous if you're mountain biking at speed, as you could end up in a ravine.


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## Peanya (Jun 12, 2008)

I don't really get rotating bike tires. By the time you need to replace the rear, the front has some wear, but it'll still give a few thousand miles more. You'd be best served to replace the back, and keep the same front anyway. 
I plan on doing the 23/25 when I need to replace tires. Just don't make the mistake of getting rare (colored) tires, as they're never in stock when you slice one up!


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## tlc4bikes (Dec 31, 2009)

Rotating tires on a bike is just like rotating your car tires (but allot easier). On your bike - the rear tire wears 2 to 3 times faster. Every 500 to 1000 miles rotate the tires. What you are looking for is noticable wear on the rear tire. When you get a flat spot down the entire center of the tire (the wear will differ from one brand to another - but it isn't rocket science) say 5 or 6 mm wide. Rotate rear to the front and when the rear has worn down to form a flat spot then it is time for new tires. I like to think that by rotating tire I keep a even grip on the tires because they are both the same age. Versus having a new tire in back and a tire up front that has been on for "thousands of miles". The front rubber my let go of its grip going into a turn because it is older than the rear time. To me it is my comfort zone and everybody should do what makes them feel comfortable.


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## eddie m (Jul 6, 2002)

I never rotate my tires. If I'm using the same size front and rear, I ride the rear until the threads show, then I put the front on the rear and a new tire on the front, or maybe I'll put 2 new tires on and save the old front for a spare. I always keep the best tire on the front because a flat on the front is more likely to cause a crash.
FWIW I don't notice any difference in traction regardless of tire wear.

em


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