Ford E450 Tire Size

Hi Jim,

At 50 mph =< 54 mph

at 65 mph =< 70 mph

I in fact drive at 78 kph currently (49 mph).

I'm really hopeful that I can make this change--it won't increase the chassis capacity--but it will increase the tire capacity.

HiTech wrote:
Did you run the calculator to see how far the speedo will be off? May not be too bad.

Jim

Pianotuna

I have 225/75R17.5 Toyo M143Z's load range "G" tires all the way around. I purchased tham as a package deal from Rickson. Just checked receipt and cost was about $3,200. That was for mounting, harmonic balancing and shipping, also included an unmounted spare tire. To me, they are worth every bit of that for peace of mind. Check the Rickson website sometime they run a special.

Did you run the calculator to see how far the speedo will be off? May not be too bad.

Jim

Hi,

I just spoke with a "tire person" and they suggested I might well be able to do the LT235/85R16 without spacers. This would give me a lot more clearance.

I phoned the Ford motorhome "hot line" and asked if it was possible. They suggested staying with the 225/75R15--but did say what I wished to do was possible.

pnichols I owe you a meal somewhere! Thank goodness for RV net.

Hi Beachcomber,

I won't have to move out the front tires--I would have to use a spacer on the rear duals.

beachcomber_1 wrote:
Everyone looks at the clearance and load carrying values, but overlook the effects of changing the geometry of the suspension. Moving wheels out with spacers changes the load point increasing stress, more so on the front suspensions. be careful and aware that this over stress on front spindles by changing offset can cause early failure.

X2

I believe the need for spacers centers around the rear duals so as to maintain adequate clearance between tires of wider cross-section than stock. As I understand it, duals should never touch each other under dynamic loads and also need enough space between them so as to provide air cooling of the inner sidewalls.

Of course, dually spacers also increase the stress on rear axles and bearings.

Everyone looks at the clearance and load carrying values, but overlook the effects of changing the geometry of the suspension. Moving wheels out with spacers changes the load point increasing stress, more so on the front suspensions. be careful and aware that this over stress on front spindles by changing offset can cause early failure.

Hi,

I do imagine that I'd need different spacers for the rear duals?

As long as it is within spec, it will actually give a better ride if it the sidewall bows a bit.