2007AcuraRL

Well with all the recent discussions here about the MMC 2009 RL, I'd thought I would ask your indulgence to change the pace back to the 2nd Gen RL for a second since I need opinions about my wheel & tire upgrade.

I am about to purchase new wheels and was planning to get 18's primarily to keep the slightly cushy ride of 45 series tires. However an opportunity has presented itself for me to buy some 19's at a good price. My concern is whether the 40 series tires I would need for those rims will give a ride that is too jarring?
Also, I have the occasional unavoidable potholes to worry about since I live in the northeast.

I know that the wheelwell gap with 19's look worse on a car without a drop, so I'd probably also do the A-spec suspension upgrade, but wouldnt the combo of the A-spec suspension and 40 series tires give too rough a ride?

Comments and thoughts appreciated....

kirbyflorida

My opinion is if you are south of Kentucky then the 40's are ok, north of that too harsh. I believe I read that anything larger than 18 inch, could be 19 though, I forgot, are detrimental to performance, getting too heavy.

Chas2

I think there is more to it than just weight.

Assuming you keep the same rolling diameter by lowering the profile (e.g., 245/50-17 to 245/40-19), larger wheels will have more mass distributed outwards from the center of the wheel making the rotational inertia greater. This means it is more difficult to start up and to stop. This is easily observed with ice skaters. They have the same the same with their arms outstretched when spinning, but when they pull their arms in they spin much faster because the mass is now pulled in closer to the axis of rotation.

So if you had two wheel tire combinations, of the same weight, but one was 17" and the other 19", the 19" has more mass distributed toward the outer edge, and has greater rotational inertia to overcome. Of course if you have lighter wheels, such as Touge's AME 19" wheels, the problem should be lessened, but I do not understand the math enough to tell you how much, etc. Maybe a real engineer can help out here.

slawek65

I have 19" BBS rims with 255/40/19 tires and a-spec suspension and I love the ride. Ride it's not much more rough then stock in my taste.

Roy Cya

I also have 19" ACE Stradas with 245/40-19 tires and H&R springs. I love the ride as well.

slawek65

Yes, I go with 255 and little more side wall

DoctorTuna

I have the 19" RonJon Legends with Michelin PS2 245/40/19. I drive in Indiana and actually have pretty good roads where I am. The ride is not significantly affected although cornering seems more planted to the ground. The exterior look of the car is the best feature though, completely changes the look and lets it live up to the SPORT luxury definition, I think. My vote... 19" with 40 series!!

2007AcuraRL

Thanks. I am leaning again towards the 19's. What color is your RL? I'd like to see a white RL rolling on the Legends.

DoctorTuna

I have the Celestial Silver RL, the 19" Legends really do complement the vehicle visually and I am hard pressed to notice a significant difference in ride quality as mentioned. I wanted to upgrade the performance and the appearance of the vehicle and I felt that going up to just 18" wasn't enough for my standards.

In regards to previous replies about rotational inertia, I'm not an engineer and can't make an argument there. One thing that is well understood is unsprung weight and the 19" Ronjon wheel came in lighter than the stock 17"!! Considering you have less sidewall with the 40 series tire replacement you have a definitive decrease in unsprung weight which improves performance dynamics. I don't know about other aftermarket upgrades but my 19" wheel/tire combination has the exact same total diameter as the stock package, 26.7", therefore no siginificant changes in speedometer readings and ABS/VSA functionality. This means that the wheelwell clearance is identical to the stock unless you lower the suspension, which would probably affect ride quality more.

In regards to potholes... don't hit them!! This isn't always possible but there is no doubt that a 40 series tire won't like them. I have hit one major hole since I upgraded, at night, and just didn't see it. No damage done, wheel and tire are fine. I wouldn't want to do it frequently though. Bottom line.... you hit a big enough hole it doesn't matter what series tire you got on!! If you're looking for a sporty appearance and are performance oriented, definitely go with the 19's!!! Hope this helps.

2007AcuraRL

thanks. Your commentary is probably just the push I needed to tip the scale in favor of the 19's. My concern about the ride becoming to harsh with 40 series seems to be not a problem. I will also consider the A-Spec suspension upgrade since others have reported this as a 'must have' upgrade and that Acura should have made it standard for the RL. I love the look of the drop of the H&R Springs that Roy Cya has on his car, but that may be too firm an overall setup for me. I dont have many fun twisty roads where I drive to and from so bump absorption takes priority over handling in curves.

BTW, I see you are new here so welcome to the Boards!