Which width touring tyres?

rpaul

Sorry, not sure if this is the right place for the question, but it doesn't really seem to fit anywhere.

Anyhoo, I am going on Lejog the long way, on a CX bike, and want to get a pair of Schwalbe Marathon Pluses; did a bit of surfing, and they seem to be all the rage.
Which width, though? 32c is a popular option, but I am concerned with the weight rating - on Schwalbe's website, it says 90 kg max; I weigh 70, bike 10, panniers can be anything up to 20 depending on how much beer is still left; overall it puts it beyond the 32c territory more into the 38c one; strictly speaking, even that would be just about within the bracket. So I don't know. I would speculate that a tyre will take more than rated weight, but at the same time, a blown tyre does not speed you up, does it? So I wouldn't mind some peace of mind.
The fork will take a 38; the weight is not that much of an issue either, what with the panniers and stuff. I am more concerned with the increase of the rolling resistance - any thoughts on how much of that will I get?

Thanks.

DiscoBoy

Increasing tyre width does not increase rolling resistance.

That said, I don't think that more than 32 wide is necessary. I have 28s Marathons (not +) on my Dawes galaxy and I have ~5kg on you.

ai_1

I haven't got any experience with the Schwalbe Marathon tyres but in general rolling resistance increases result from the tyre thread and tyre stiffness, but wouldn't be expected to increase because you go for a bigger size. If anything a larger tyre at an appropriate pressure will likely have lower rolling resistance. Bigger tyres may be worse aerodynamically but that's unlikely to matter much if you're touring with panniers.
If you want to minimise rolling resistance you want soft flexible tyres with a fairly minimal or slick thread. MTB tyres have high rolling resistance on the road because of the nobbly thread, not because of the width.
The Marathons are probably not the best for low rolling resistance anyway given that they're focused on puncture protection and general durability. As a result they'll have a heavy carcass with protective belts of durable rubber or plastic which will make the tyre much stiffer and thus increase rolling resistance. If you want a smoother easier ride there are probably better tyres but it's a trade off between ride and puncture resistance. If the roads are likely to to be littered with thorns, flints and glass then stick with the marathons. I've historically gotten very few punctures on the roads I ride (approx 1 puncture every 4000km on average) so I've recently changed from tyres like the Conti 4 Seasons (reasonable protection but less than the Marathon and far lighter and more flexible) to lighter race tyres. So far no punctures after about 600km+. We'll see if that continues!

rpaul

Cool, thanks guys. It helps a lot.
P

ugo.santalucia

32 is good. Can't praise enough the Vittoria Randonneur PRO