205/55R16 - A question

[Hawkeye]

I need some advice...will 205/55R16 all season tires fit on my 2009 Clubman or do I need 205/50R16 tires only? THanks in advance.

[cmcveay]

Hawkeye,

I ran the two sizes through the tire size calculator and the 55R16 will be approximately .8" larger in diameter and I think that will make it pretty close to being too much tire for the wheelwell. With that kind of profile, you'll be likely to find the front tires rub inside of the fenderwell when you make a turn at the steering locks. The rear tires may end up rubbing at about the 2 o'clock position of the rear fender wells when you hit road surfaces that compress the suspension. The increased diameter will also be about 3% more than OEM and that'll change your speedo reading - which is another discussion all by itself.

 

My other concern with going to a 55 profile tire is the increased amount of sidewall. It's certainly going to give you a Wayyyyy more comfortable ride down the road but you are very likely to find that you are unhappy with the way the car reacts when you get out into the twisties or you need that snappy response that we all love in our cars.

 

The additional sidewall is going to "squirm" and roll when cornering and with the extra rubber between the wheel and the road, it's going to take more steering effort to get the same amount of deflection.

 

Another DCMM member who shall remain unnamed recently made a very similar change and the first time they took the car through a familiar turn at a familiar speed, they were very surprised at the amount of understeer and the reaction of the car (or perhaps, that was a lack of reaction). I won't repeat the expletive they quoted themselves as saying but if you heard it, you'd know they were surprised...

 

I'm one of those guys running tires at the extreme edge of what'll fit (I'm running 235/40R-17 Star Specs which are wider than most for that size) and I'm not sure I'd be willing to plunk down the cash for tires in that size unless they had some mounted up to trial fit/drive.

 

Anyone have any experience with 55's?

[Hawkeye]

Craig: Thank you for your insights. I just wanted to make sure before I take the plunge. I am looking for a way more comfortable ride and am considering both Bridgestone and Michelin brands...seems like I can get a good price at Costco. Any sense as to whether the TPMS used in the 2010 model wheels will work with the internal system in the 2009 model? I have a very good set of MINI 2010 wheels with TPMS and want to use them on my Clubby.

[cmcveay]

From what I have read and been told, you'll be good to go on the TPMS sensors for '07-'10 models but for '11, the they were changed and the new sensors don't play well with the "pre-refresh" 2nd gen TPMS system.

 

I know what you mean about searching for a more comfortable ride. In 2009, I lowered Archi with springs and because I failed to cut down the height of the front/rear bumpstops on the OEM struts, I ended up with about 1" of suspension travel on the OEM 205/50R-16 runflats. The ride of the car took a serious hit, as did my spleen, kidneys and spinal column.... I went to a 215/45-17 non-runflat all-season (Kumho Ecsta ASX) and the ride did improve a little but I had an issue with the rear tires rubbing at the rear edge of the wheel wells. In January, 2010 an unidentified miscreant left Archi on Cinder blocks (they stole all 4 wheels and tires) and I replaced them with a set of 235/40R-17's (also non-runflat Kumho Ecsta ASX's) and I was pleasantly surprised to find that the wider tires on the 7.5" rim really improved the the ride and the lower profile improved the handling (I drove them through all of the January/February 2010 snow, a summer of autocross and all of the club events). This spring, I replaced those tires with the same size Dunlop Star Spec Direzza tires just to try something new. This past Sunday, I did a significant modification to the suspension of Archi: I replaced the OEM struts with Bilstein HD's all the way around and I swapped out the Mach V Technic springs for a set of NM Engineering springs Alpha springs. The net change in the ride height was that the car is now 7/8's of an inch higher in front and the same height in the rear (still about 1" lower than OEM all around) so it has less rake and my front airdam now clears most speedbumps in parking lots. This time I DID cut down the rear bumpstops about 1". The front struts have internal bumpstops and I have a pictures of the difference in the hydraulic piston up front, it's easily twice the diameter of the OEM strut.

 

Now, I don't get the bone jarring, internal organ bruising jolt on expansion joints and pot holes, I get a subdued "thud" and the dips that used to cram my skull into the sunroof now give me a little jostle to let me know they were there. I've also run the car through my "test course" a couple of times and I can say that the improved compression and rebound dampening in the struts and the incredible grip of the Star Specs give a whole new meaning to the expression "drives like it's on rails". Ripples/bumps in turns used to be a what I would call "exciting" at best and, at times, just plain scary. No more. The suspension just eats up the bumps and the tires seem to stay planted.

 

Costco has great prices and a pretty wide selection of tires if that's where you choose to shop. A great website to shop and compare and even read user reviews is www.tirerack.com. Tire Rack will also drop ship to your home, a garage (such as one of our vendors, Mach V) where you can get the install done.

 

Good luck with the decision making process and I can tell you that a comfortable ride can be had without any (or maybe just a little) compromise in the handling that we love in our cars!

[Mr EZ]

Craig,

 

I just got some 205/40R17 G-Force KDW. I'm going to have to adjust the odometer to compensate?

[cmcveay]

Enrique,

What size did you change from? There's no no "adjusting" the speedo unless you've got the NCS Expert software and all.

[Edge]

Enrique - responding to the same basic question you emailed me:

 

You shouldn't have any problems other than the speedo and odometer being further off. A "lower" profile tire will sit less tall, which means they have a smaller diameter and circumference... so they won't rub on any fenders or anything like that.

 

Using the very popular (and free!) Miata.net Tire size calculator, a change from 205/45R17 to 205/40R17 means the following in terms of speedo:

 

Speedometer reading with non-stock tire size is 3.3% too fast. When your speedo reads 60mph, you'll actually be traveling 58.0 mph.

Now, this also means your MINI will be putting more miles on the odometer than you're actually driving. In addition, don't forget that MINI deliberately sets the factory speedo about 2 or 3 mph fast in the first place, so you'll actually end up with a speedo that is set 4 or 5mph too fast on the highway! (the MINI-set speed increase does not impact your odometer though)

[cmcveay]

That would be kind of funny. "Wow, I'm doing 75mph and everyone is FLYING by me...." or "Hmmm, I'm driving 65, why does it take so long to get there?"...

 

+1 for the Miata tire size calculator, it's been a great help visualizing the difference between tire sizes. Since I didn't know the tire size that Enrique was changing from, I hesitated to post the potential difference but you are correct. Going to a 40 from a 45 on the same wheel size will give you a "shorter" tire which will require more rotations per mile, throws off the speedo calibration and, it would probably hurt your fuel efficiency as it will require a higher RPM to maintain the same speed.

[Mr EZ]

So is there any way to recalibrate the odometer? Th speedo is fine, nit I think it works anyway???

[cmcveay]

Enrique,

Is there an inexpensive and effective way to recalibrate the odometer? Not that I know of right now. That answer may change in the near future. Don't you hate the suspense already?

[Mr EZ]

There may be more hope at the Dragon if you are going this year. I think a couple of the people who have "cracked the code" on this project are going to be there.

 

WOW Craig, that is a real nice way to get my hope up....................

 

Enrique,

Is there an inexpensive and effective way to recalibrate the odometer? Not that I know of right now. That answer may change in the near future. Don't you hate the suspense already?

Edited April 14, 2011 by cmcveay