Tires/chevy step van
is it possible to use 225 70 19'5 insted of 8-19'5
tvin tires back it,s on a 1979 chevy p 30 stepvan
regards klas lindkvist sweden
An 8-19.5 is 8.0" (203mm) wide on a 6" rim, with an allowable rim width of 5.25" to 6.75", a diameter of 33.8" (859mm), a minimum dual spacing of 9.1" (231mm), and a load carrying capacity of 3195# at 95 psi - Load Range E (1449 kg at 6.6 bar)
A 225/70R19.5 is 8.9" (226 mm) wide on a 6.75" rim with an allowable rim width range of 6" to 6.75", a diameter of 33.0" (838 mm), a minimum dual spacing of 10.0" (254 mm) and a load carrying capacity of 3195# at 80 psi - Load Range E (1449 kg at 5.5 bar)
So the answer is maybe.
First, adjusting the width of the 225/70R19.5, it is 8.6" (218 mm) wide on a 6" rim - so it is 0.6" (15 mm) wider. That might be a problem.
Looking at the other dimensions:
Diameter: the 225/70R19.5 is smaller in diameter (2 1/2%). That means the speedometer will be off (You'll be going slower than indicated by 2 1/2%.)
Allowable rim width - if you have a 5.25" wheel, the 225/70R19.5 will not work.
Minimum dual spacing: The 225/70R19.5 requires 0.9" (22 mm) more width, BUT the rim widths are difference - and adjusting for that, the 225/70R19.5 requires 0.6" (15 mm) more when mounted on the same wheel.
Load carrying capacity - Use the same Load Range, but the pressure can be 15 psi (1.0 bar)lower.
So here's what you need to know:
1) What is the width of the rims? A 5.25 means no - no interchange. That dimension should be stamped on the back side of the wheel - and usually it also has a letter following it that indicates the kind of flange the wheel has : Possibilities are none and W.
2) A 6.0" rim width means the minimum dual spacing needs to be 9.7" (246 mm) - AND - there needs to be at least 3/4" (19 mm) clearance around the tire currently being used to be sure the 225/70R19.5 doesn't rub. Please note: Measuring clearance on the rear is pretty straight forward, but the fronts require the suspension to be fully collapsed and fully turned (in both directions) - and that is not easy to do. It might be best to work with someone who is willing to look carefully at this.
Note: I'm not going to calculate what is needed for the other possible rim widths as it is likely the wheels are 5.25 or 6.0". If I'm wrong on this, post a reply and I'll do those calculations as well.
3) And you will need to use the same Load Range.
OK, I am now going to go back and add the metric units where appropriate. Please note that rim width are always in inches.