RV 8 wheels

[67pileit]

I'm thinking of buying an RV8 and would like to operate it into a rough grass strip. A friend with an RV4 has flown his aircraft into the stirp and says the vibration is too hard on the airframe. Can one put larger tires/wheels onto an RV8 to sovle this problem? Thanks

[scsmith]

Hi,
welcome to the forum, first of all!

There are other threads in the archive on this topic, but I will summarize for you:

A few people have put 600 x 6 wheels and tires on. I think it may be tough to fit the wheel pants on such big wheels, but if you are frequnting rough fields, you probably don't want the spats on anyway.

A middle option is to use somewhat bigger tires on the standard 5" wheels. Folks are using the 380 x 150 x 5 tires, which are about an inch bigger in diameter and a fair bit wider too. This provides a pretty significant increase in tire, but still fits in the wheel pants, is easy to switch back to std tires if you like in the future. This is what I am doing.

I positioned my wheel pants about 1/2" higher than the instructions say, so that the 380x150x5 tires will fit inside, and the combination of the higher fit and the bigger tire gives lots of clearance from the wheel pant to the ground, so it doesn't get beat up on gravel, grass, etc. Would still be vulnerable in very soft/muddy situations, but I hope those are very rare for me.

Also, if you plan on a lot of rough field ops, I strongly recommend you substitute the stronger nuts on the landing gear leg attachment bolts. There is a very long thread on that topic, you will have to sort through the chaff to get to the important info, but could search on NAS1804-6 to get you started.

[67pileit]

Steve,
Thanks very much for this information, I'll search for the other threads.
I appreciate your time.
Chris

[chaskuss]

Chris,
Using 6" wheels requires using 1.5" diameter axles. Your 8 comes with 5" wheels, which use 1.25" diameter axles. The RV8 is the only 2 seat model of the RV line, which allows you to change out the axles.
So the answer is YES, you can put 6" wheels on your 8. You will need to replace your axles to do it.
Charlie Kuss

[Ironflight]

One other thing to remember is that you friend with the -4 has a completely different type of landing gear arrangement than on an -8. The -4 has a rod-shaped gear attached to the engine mount, and the -8 has a flat steel gear mounted to the fuselage. While I agree that the stock airplane is not ideally suited to rough fields, I would be hesitant to take action simply based on comparisons to the -4....the first time I saw one taxi up to me on a rough grass strip and I saw the springiness of the gear and the way the wheel move relative to the airplane, it scared the heck out of me! The -8's gear doesn't bounce around in quite the same fashion.

Paul

[Andy Hill]

67pileit

Good advice above.

We have the 380x150x5 tyres... and they can be run from 15psi to 35psi according to what you want/need.

Given your initial concern <<and says the vibration is too hard on the airframe>> low pressure should help... However, once you have swppaed the main tyres as above, the tailwheel becomes an issue. The aft end of RVs can crease / take a beating. Similarly, 2 up our RV-8 causes more strip damage / furrowing from the tailwheel than the main wheels.

Summary: the 380x150x5 tyres are an "easy" modification, in fact, hardly that. If you need to go to 6" wheels / tyres, you might need to look at a "fat / low pressure" tailwheel as well?

Andy
RV-8 G-HILZ

[sf3543]

You might want to research the nose gear issues that RVs have been having, also.
You may think twice about operating an 8A on a rough or unimproved strip.

[John Clark]

Originally Posted by sf3543

You might want to research the nose gear issues that RVs have been having, also.
You may think twice about operating an 8A on a rough or unimproved strip.

Um, sorry, but the question that started the thread was regarding an RV8, not an "A"

[Andy Hill]

Further to Paul's post, the RV-4 has had issues with the gear/engine mount cracking, either through apparent heavy landings or general abuse i.e. rough field. The RV-8 will not have this exact issue... It might be worth clarifying

A friend with an RV4 .... and says the vibration is too hard on the airframe

the exact basis for his assessment? Is it RV generic? Or specific to the cracking issue?

[67pileit]

Thank you all for your inputs. My first time doing this and I am at the bottom of the power curve. I'm very impressed.

Chris