Bolt circle question

[GuitarPhotog]

It seems that wheels are specified by the "bolt circle" of the lug bolts. However it's difficult to empirically determine the bolt circle once the hub is installed on a trailer.

Is there an easy way to determine the bolt circle, maybe from center-to-center measure of the lug bolts? I need to get a spare wheel and tire for my trailer and don't know what size wheel except that it's a 15" rim.

After one year, 5 trips, and over 2500 miles, I suppose I should carry a spare wheel and tire




<Chas>

[Larry C]

It seems that wheels are specified by the "bolt circle" of the lug bolts. However it's difficult to empirically determine the bolt circle once the hub is installed on a trailer.

Is there an easy way to determine the bolt circle, maybe from center-to-center measure of the lug bolts? I need to get a spare wheel and tire for my trailer and don't know what size wheel except that it's a 15" rim.

After one year, 5 trips, and over 2500 miles, I suppose I should carry a spare wheel and tire




<Chas>

Here ya go:

http://www.trailerandtruckparts.com/assets/images/boltpatterntemplate.pdf

[Martiangod]

Measure from the outside of one stud, skip one to the center of the 3rd

[GuitarPhotog]

Thanks Chris, I'll try that tomorrow and report back.

Larry, I don't think the template will work because the trailer uses ca. 1948 passenger wheels and tires, but I'll print it and check that tomorrow and report back.

<Chas>

[Dale M.]

Thanks Chris, I'll try that tomorrow and report back.

Larry, I don't think the template will work because the trailer uses ca. 1948 passenger wheels and tires, but I'll print it and check that tomorrow and report back.

<Chas>

Some things never change.....

Dale

[GuitarPhotog]

OK, so is there a standard wheel that uses 5 holes on a 5-1/2" bolt circle? Because that's what my measurement seems to give. Unfortunately my caliper won't open farther than about 5", so more precise measurement will have to wait until I can get the wheel off the trailer.

Thanks to those who helped.

<Chas>

[dguff]

Ford cars used a 5 by 5 1/2" bolt circle from 1928 to 1948. I would bet you have Ford steel wheels. That bolt pattern is also used on Jeeps until the late 1980's, Ford Broncos and F100 pickups and Ford vans up to the late 1980's, International Scouts and Travelalls, Lincolns in the 1950's and Mrecury's to 1951. Your best bet for a spare would probably be a junkyard where you could get a wheel from a Ford Bronco, pickup or Jeep.

Jerome

[dguff]

By the way the wheels on the trailer in my avatar are Ford 5 by 5 1/2 but they are 16".

Jerome

[Martiangod]

Lots of choices for 5 x 5 1/2 bolt pattern

Roadkill customs has the best wheel cross reference I've found so far

http://www.roadkillcustoms.com/hot-rods-rat-rods/Wheel-Bolt-Pattern-Cross-Reference-Database.asp?LugCount=5&StudSpreadInch=5.5&StudSpreadMM=

[GuitarPhotog]

OK, how do I figure out how wide a rim I need, and how much offset I can/can't tolerate?

My tire size is P205/65R15. I thought that meant profile 205, 6.5" rim width, 15" rim diameter.

My tri-spoke cast alloy rims, that came on the trailer when I bought it, seem to be about 8" to 8-1/2" wide at the rim. I can't measure well until I get a wheel off the trailer. And, there seems to be about 4" of wheel outside the hub flange, i.e., the hub flange seems pretty centered in the rim.

I suppose much of this is moot, because I just need to know enough to go to the junk yard and buy a rim, and to the tire store and buy a cheap tire to fit it. But it's always good to understand what's going on, in case something goes wrong...... goes wrong...... goes wrong.....

Thanks to all for the help so far



<Chas>

[KCStudly]

Go here for an explanation of metric tire size designations.

65 is the aspect ratio, not the rim width.

There was another recent thread (and I'm sure old ones before that) where it was also pointed out the axle hub face to trailer frame and/or cabin clearance (or trailing arm clearance, if you have a torsion axle...probably not an issue on an older rig like yours) are a big deciding factor on wheel offset, width, and tire section.

[GuitarPhotog]

Thanks KC, that helps. My trailer has a straight round tubular axle in leaf springs, with a couple of ancient shocks. The fenders are quite deep ~10 inches, and the current tires have lots of room around, so anything similarly sized should fit with no issues.

This is just for a spare, after a year and 2500 miles of trailering, I decided I need one

Thanks for the help


<Chas>