Feedback on Changing tires sizes?

[Turbodime]

 
My RV is sitting on 8 Kumho 225/70-19.5 tires with a date code of '03. The tires are in excellent condition for the age but to be on the safe side, I plan on replacing the fronts this month.

The OEM tire size was 8R19.5 and the PO installed 225/70-19.5 tires. This is all fine and dandy, but the front hydraulic leveler’s wont swing down due to them coming in contact with the ground.  I assume this to be two issues. Front springs have sagged as well as the reduced tire diameter from 33.8” to 31.9”.

I plan on replacing the front springs in the near future.

Another small issue, the RPM’s of the 454 is dead on at 3k doing 60mph (GPS).

I would like to run this rig down the road at a lower RPM in the 55-65mph range and going back to the 33.8” tire would drop my RPM’s.

For those that have made the swap from 8r’s to 225’s are you happy with the outcome or did the increase in RPM’s reduce MPG?

As far as brand of tires, I'll probably be going the Samson route.

Here are the specs to the three popular 19.5” tires.

 

[Stripe]

Every now and then I would encounter the same problems with my landing gear.  I did a spring replacement on my HR Imp.
Here is the write up. It's sooo easy..    And I realized a good 4 inch lift recovery..


http://www.classicwinnebagos.com/forum/index.php/topic,7759.msg36431.html#msg36431

[Stripe]

You're welcome, Sie Sind Willkommen, Bu ka Qi, Walang Anuman!

[bluebird]

Before you make up your mind about what size tire you buy, you need to measure your wheels. Your wheels may be too narrow for the 225 or the 245 tires. I forget what size my wheels are but they are too narrow to put larger tires on. I didn't like the 8r19.5 tires because they looked too narrow so I was going to go with a 245. The dealer refused to install a 245 on my wheels. He said if I wanted larger tires from him I'd have to have the correct size wheels. I've since driven a coach with the larger tires, and my coach handles better, that coach was 9"  taller than mine though.

[ClydesdaleKevin]

Problem with going to the metric size, besides the fact that they are smaller in diameter, is that they are wider than a standard 8R19.5.  No problem on the front, but VERY bad for duellies on the back!  They often come in contact with each other, which is bad juju and a sure fire way to get a blowout on the highway.

Kev

[Turbodime]

225-19.5 are on currently with plenty of room between the duals.  I've gone on two short in state trips with one to Lake Plesant pulling my 24' pontoon and another up to Oak Flats.
Lake Plez trip I averaged 5.4mpg and the Oak Flats trip 6.7mpg with gen running a/c on both trips.

The shorter tires were welcomed on the climbs but the 3k at 60mph on the flats made me wish I had a 4l80e. I doubt I would get better mileage I just want the engine to run at lower rpm.

I'm going to stay with the 225's and put new springs in the front to get back to stock ride height.

Thanks for the replies.

[Rickf1985]

I am coming into this late but if you go more than 2 inches wider than the rim width then the bead of the tire will not sit square on the rim and will be moving the whole time you are driving. This is never supposed to move and a blowout is a very good possibility. If you are very lucky you will just get a bead leak. You say your tires do not touch but you cannot see them in driving conditions when everything is constantly changing. Every dip in the road substantially increases the load on the tires, almost double for just a small dip at interstate speed. I will bet the tires are kissing in those circumstances. Not really an issue unless you have a piece of gravel or road debris fly up out of the same dip. You could end up with a double blowout!

[Turbodime]

I've double checked and there is 2.5" between them with no sign of them 'kissing".   As far as rim to tire spec the 225 are fine for my rim. It's the 245's which would be out of spec, and I would only go that route if I had a single axle in the rear and the correct rim.

There is a local company in Apache Junction, AZ that has 8R's Samson's for $189 installed.  The 225's are a couple bucks more.  Company name is Reids Tire.

357 S Winchester Rd,
Apache Junction, AZ 85119
(480) 983-6508

[ClydesdaleKevin]

LOVE my Samson tires!  Have a lot of miles on them now, and highly recommend them!

Of course, the 4x4 bug has a hold of me now...I wonder what larger rims with mudder tires will fit my bolt pattern?  Or if someone makes a big 19.5 offroad tire?  I have LOTS of room under the wheel wells...lmao!

Kev

[Oz]

If you're asking for advice on that, please make it a new topic in the General forum.