change of tire size

I guess I did things wrong all my life. As a kid when 70 series tires were introduced I just had to replace my 78 series. Got a rougher ride.

The when 60 series came out, I very wisely traded in the 70 series for the sixties and made things even worse.

IMHO ride-wise I don't think you are going to notice much of a difference.

Hi Capri,

I've checked the spacing. I have 10.2. How do I get to 10.75? New rims? Spacers?

Hi j-d, Thanks for the heads up on the "pilot portion" It is an E-450.

Careful, Kids!

A spacer will probably leave the studs too short to hold simulator nuts, maybe too short to fully engage the lug nuts. Also, spacer just might (check to be sure) shift the outer dual wheel away from the pilot portion of the hub. These wheels use "loose" stud holes because weight rides on a raised diameter part of the hub.

Hi Capri,

Thanks for the numbers. I'll check that out.

And can a spacer between the duals be added to give that extra clearance?

pianotuna wrote:
Hi all,

If I go to LT235/85R16 from LT225/75R16 what differences might I expect in handling?

The new tires will be installed on a 28'5" Class C on E-450 chassis with V-10. It weighs in at 14,000 lbs fully loaded with two people.

First, I'll bet your rear wheels don't have enough offset to accommodate the wider tires. There is a minimum dual spacing needed for tires and most vehicles come with wheels that are very close to the minimum. This is important because if the rear tires touch, they can fail.

Tires are designed to flex in a certain way and when they touch in a dually (a common term is "kissing"), the sidewall stress is different and changes the tension in the tire plies to go into compression - very bad.

You can check the rear dual spacing my measuring from the center line of one tire to the centerline of its dualled partner. For an LT227/75R16, the minimum is 10.2" - and for an LT235/85R16 it is 10.75"

You might want to look at a "Tire Pressure Guide" and check the minimum wheel offset required for both tire widths.

I have seen 215 mm tires replaced with 235 mm wide tires, and you get the tires touching on the bottom, something that will cause tire sidewall wear. You will need rims with a additional 3/4" offset.

Fred.

I bet 65 is high in front for a 14k weight vehicle unless you have scale numbers to work from. I did Alcoa wheels and Bilsteins in my 14k weight C. Big improvement but If I had it to do over I would have put the soft Bilsteins up front and run 55 lbs up there. All the weight was in back. I suppose I would have run tall tires in back and normal up front too.

Sounds like you are on the right track.

Jim

Hi Jim,

I have worn out Michelin's at the moment. Need a wheel alignment. Shocks have 102000 kilometers (61,000 miles) on them. Manual rear air bags at 60 psi. I run 80 psi in rear and 65 in front.

My mistake- definitely better on taller in the same grade of tire. A little less connected handling though unless grip is better on the new tire. Be sure to set tire pressures on weight, especially up front where weight is lighter than most think on a C near the limits.
The extra sidewall should help the ride. Handling may be a little softer due to the extra flex so watch the corners.

Jim

Hi Jim,

Are you saying ride is better with a shorter tire--or better with a taller tire? I think you win the bet on the ratio.