Tires Beaver AG tire sizes?

[KenBer]

What is the normal AG tire size for a S370D Beaver? I currently have 5-12 up front with 8-16 in the rear. I was looking in the Satoh Beaver Parts Manual and it lists 5.00-12(Front) & 8-16(Rear). I need to get new tires and I know there is a difference between the 5-12 (20.8" OD) & 5.00-12 (23" OD) -- (Who's bright idea was it to make them different??? ) My front tires are extremely worn in comparison to the rear, so I'm thinking the tires are the wrong size. What does everyone else have?

Thanks,
-Ken

 

[KenBer]

To add more complexity to this issue - my Owners Manual lists the front tire as a 5-12, while the Parts Manual lists 5.00-12...

I'm going to try and breakout the jackstands and some measuring tapes tonight to run this thing in the air and try to measure the ground coverage differences between the front and rear tires. I know from reading some other posts, the front tires should have about a 3% maximum lead on the rear tires. with some trial and error and some calculations - it should tell me which tire is the right size based on the gear ratios. After all, the 5-12 with a 20.8" OD will run 65.34" per rotation, while a 5.00-12 with a 23" OD will be 72.26" -- it should be fairly easy to see. I'll post what I find out.

 

[KenBer]

Well I checked some things out last night and found that a 5-12 tire runs at about 98% of the rear tires. The hangup is that a 5.00-12 and 6-12 (almost the exact same OD) will run at about 108% of the rear tires. I'd really like the front tires to be pulling, more than dragging - but I'm afraid the 8% overage is too much. Any suggestions?

 

[modifyit]

Sounds like the tests you are attempting should be done with new tires properly inflated to get baseline numbers. If your tires are worn or improperly inflated you are going to get variations. In any case I suppose some wheel skid is common even with a new setup.

 

[SATOHBULL]

One thing that may be confusing is the fact that OD x 3.14 is NOT the rolling circumference. It is the static circumference when unloaded but you must use the actual rolling circumference in your calculations. This can be measured directly on a hard surface or taken for the tire maker's data.

 

[SATOHBULL]

Mor info: I just checked a 5x10 on the Firestone site. The calculated circumference is 65.31 vs 63 rolling circumference. Quite a difference.