Clarkeyboy

Hi guys, first post, great to find this forum gonna learn so much from you all! I’ve ust bought my first serious bike and think I might have made a mistake so I wondered if I could fix it without swapping the bike because I think it looks great. I have the Specialized Sirrus 4.0 (not the X 4.0) and I use it split 50/50 on pavement and gravel / grass (nothing serious just cycling with the family) and the tyres seem too narrow they are 32mm wide. I realise that the X 4.0 would have been a more practical choice but I prefer the gears on the 4.0 for faster road use. I wW ondered if I could put wider tyres on it like the X 4.0 has? Does anyone know if I can fit the 38mm pathfinder or equivalent tyres? Many thanks guys

hokiefyd 

You can measure the distance between the chain stays yourself to see. The rear tire will probably have the tightest clearance, probably down between the chain stays. I'm pretty certain you could fit a 38mm or even 40/42mm tire on your Sirrus. Your Specialized dealer will know for sure, and may even offer to test-fit a tire for you. Another thing you can do is remove the tire from the rear wheel, inflate just the tube itself to the tire size you're considering (perhaps about 40mm across) and slip the wheel in the frame and see if the tube has clearance at the tight points.

lelenz

A couple months ago I agreed to purchase for my son a 2021 XL Sirrus X2, when the shop unboxed it, it was damaged beyond use. The shop also had a 2021 Sirrus 2 in an XL frame. They offered to put the Sirrus x2 wheels and tires on the Sirrus 2 and they fit just fine. If I remember correctly, they even were 40mm, a tad bigger than my 2020 X4 38mm's. so I'd guess you have a good chance of making that happen, but can not say with certainty.

Clarkeyboy

Thank you for the advice looks like I can fit a 40mm comfortably front and back. Will I still be able to ride ok on the road with 40mm tyres?

travbikeman

Yes! But depends on the tire on how much road noise you will have. The more tread you have, the noisier it will be, slower riding and more tread wear you will have.

Specialized has some nice tires that offer a combination of road and gravel capabilities. The only problem is trying to find a 700x40. Typically you will have more choices with 700x38 or 700x42. 700x40 is a bit more difficult to find. Think non existent at Specialized.

Example of nice tires:

https://www.specialized.com/us/en/pa...BoChxcQAvD_BwE

Here are some 700x40's:

https://www.biketiresdirect.com/sear...&fcat=&dcnt=64

Clarkeyboy

Thanks for the advice gonna go for the 700x38 a good inbetweener. Thanks for your advice