4.0 tire 3.25 rim

Can I put a 4.0 tire on a 3.25 rim? its a Dunlop k70.

how are you measuring the rim ? is 3.25 the tire was onnit?
what bike is it ?

Yes the tire I took off says 3.50-18 and the new tire says 4.00s18 4p.r. The bike is a 1975 honda xl250 the rim is off a 1975 xl175 I'm building a cafe.

measure the rim between the inner edges where the tire seats it will be either 1.85 or 2.15"
is this rear or front ?

why are you lacing in a xl175 rim to a xl250 wheel ?

Well i spent a week cleaning up the old wheel that sat for 20yrs, I spent $50 on replacing broken and rust frozen spokes for the 250 rim which was a pain to find, waited two weeks for delivery ordered the tire it only took a week, by then had the 250 rim laced put it on the truing stand found out it had a slight bend and a nasty hop, took three hours trying to carefully straighten the thing had it pretty close, "pop" there goes two spokes which are the b spoke not available any more unless I spent more than I care, so I poked around found a guy selling both front and back wheels complete for $50 so luckily the spokes are the same, the reason for wanting the 175 rim is it's dead true and hella clean all I have to do is swap the hub.

if the rim is 1.85 it is really too narrow for the 4.00 tire, you need a 2.15 rim

Avon has a good resource for recommended rim sizes relative to tire size. The minimum recommended rim size for a 100mm wide (4 inch) tire is 2.15.

http://www.avonmoto.com/products/street-bias/roadrider

yeah the xl250 has the wider alloy rim 2.15 versus the steel 1.85 of the 175

Well not exactly what I hoped for, but good info thanks, any ideas how to straiten a rim?