Hi all. Please help as im complete novice.
My hybrid bike has

700 x 38c tires

Im looking to put some thinner and slicker tires on it to get more speed

It this possible or would I need new wheels ??

And if it is possible. How skinny could I go and what size would that be ??

Many thanks in advance guys.

You can install any (almost) 700c, or xx-622 tire where the first two numbers are the width, ie. yours are 38-622. There are practical limits, based on the actual rim width, which based on the existing 38mm tire probably isn't all that narrow.

Below is a chart showing rough guidelines for mixing tire and rim widths. Note that the rim dimension is the inside width which is 3-4mm narrower than outside width. Without knowing your exact rim,I would guess that you could very safely go to 28mm tires, possibly narrower.



BTW- there's plenty of debate about whether narrower tires are faster, or best tire width and pressure based on your weight, and I'm not going there except to suggest that you'll get measurable improvement by changing to slicks, then can get some (maybe) with a narrower or higher pressure tire.

The 700 means 700C. This is a designation for the diameter of a standard modern road wheel (it is based on a French system for classifying bike wheels, don't worry about that). The 38 is the diameter of the tire in millimeters. As far as how narrow you can go, that depends on the width of your rim. You can measure that yourself.

Some typical tire widths are 35, 32, 28, 25, 23. Your rims are probably a bit wide, so I expect you can go to 28mm for sure, maybe 25. For a recreational rider on a hybrid, I think 28 to 32 mm tires are a pretty good compromise in terms of balancing speed and comfort, depending on the weight of rider and bike.

I see FB beat me to the punch. I think Bike Forums might be wired directly into his head. I gotta quit posting here.

I was in sort of the same boat, I went with 700x35 Specialized Nimbus...they have worked well so far.

IMHO a hybrid (I have a Trek 7200 myself) is not very "Aero" to begin with, tire width does come into aerodynamics but is probably not a huge factor for most riders :-). If your existing tubes are OK you might be able to use them in 700x35 tires, but would probably need new tubes if you went much smaller ??

I have thought about narrower tires than 35 but it might snow before I can wear the 35's out this year :-).

Bill

Measure the external width of the rim in the bead area.
Stay a couple mm wider than that.

The hybrid bike is not built for max speed. Try something with drop bars. Are you racing? A lighter tire with smoother tread might be helpful. What kind of bike and tires are you using?

IDK, if going narrower is going to give you much more speed. The difference between 38 and 25 (most likely narrowest you could go, if that) isn't going to be that great. You will probably see most of the difference just changing between tread types than you will width. IMO, tread type is a bigger difference than width unless you are talking going from MTB width to roadie width.

I replaced the fatter OEM tires on my old Trek hybrid with 700x28 Continental Ultra Gatorskins. I thought I gained some speed, I don't know if it was because of the narrower tires or the higher pressures that they can handle. I've read that the Gatorskins are not particularly "fast" because of their construction so maybe I could have gained more speed with different tires, but I haven't had a flat in the 3 seasons that I've been riding them.

this should ans.your ques.:Tire Sizing Systems

Tire width isn't as much a factor in speed as tire weight and design. I tried Specialized Hemisphere Armadillos in 700 x 38 on my hybrid and I kid you not, I kept checking to see if I had a low tire or the brake was dragging. Those tires were heavy and very stiff for 38mm. I went to 700 x 40 Schwalbe Smart Sams. Still not a light tire but what a difference. The ride is much more comfortable and the wet cement feeling is gone. On my road bike I swapped from Specialized All Condition Armadillo Elites (which had been my preferred tire for the past few years) to the Bontrager AW3 Hard Case Lite staying with 25mm width. Again, a significant improvement in comfort and speed. Not earth shattering increases, but 1-2 mph average gain on 25+ mile rides. Not bad considering I'm still riding a puncture resistant all-weather tire, not a lightweight racing tire.

Not knocking the Armadillos in the least, I bought them because I wanted bulletproof fully knowing they weren't going to be fast tires.

I've had 28mm Armadillos on my Mavic A719 rims which is the narrowest tire Mavic recommends for that rim. Despite significantly reduced width, they weren't that much faster than my Schwalbe 40mm tires.