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Discussion Starter #1
Hello,

I have a 2012 Passion and looking to buy 4 new tires. I currently have 165/15 front and 185/15 rear. What is the best size for a smoother ride? I am looking to stay with 15 inch rims.
 

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Many of us have gone to 4 rear wheels on the 451, which allows you to run wider tires all around and be able to rotate them, as well. Many more have switched to 6" wide after market rims all around. With the stock front wheel size, you can go up to 175/55-15.

I personally went to 4 rear wheels with 195/50-15. The difference is night and day!

There are many threads here about tire and wheel sizes.
 

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you could go with 185/60-15 or 195/55-15 all around, or you could go up to 205/60-15 for the rear tires, the rear has larger wheel wells. just make sure the front tires stay under 24 inches in diameter. you'll have to use 5.5 inch or wider wheels up front.
 

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If you don't want the expense of adding two new wheels, look for tires with a higher sidewall ratio, say 65 as opposed to 55 or 60. The additional sidewall height gives more flex than the lower ratios. Just make sure the overall diameter of the tires is within a few percent of the stock sizes or you'll have issues with the stability system. You can discuss with the folks at Discount Tire or Tire Rack and they should be able to find tires for your smart. :)
 

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Discussion Starter #5
Thank you. I wish I could try tires on like I do shoes. Do your tires rub when making tight turns?
 

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Thank you. I wish I could try tires on like I do shoes. Do your tires rub when making tight turns?
i currently have 195/50-15's that are 40mm wider in the front and 20mm wider in the back, no rubbing problem in 6+ years. i just ordered 185/60-15's to replace them, i'll get those installed this friday, i know a person who has 185/60-15's in the front and has no problem. :D
 

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i just got my new 185/60-15's, they're 1 inch larger in diameter than the 195/50-15's and fit fine. while at the tire rack, the car next to mine was a honda insight, which is more rare than a smart, and it had a humorous license plate, especially as it was suspended by 4 jacks, so i took a pic of it!
 

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Those new tires really fill the wheel wells nicely. Looks good!!
before i drove it, i turned the wheels to "full lock" and could still fit my fingers between the tire and the front wheel well, so i have about 1/2 inch clearance, only drive slowly at "full lock". the tires are quiet as well, when on the highway with the old tires i had to play my radio at volume "14" (smart model 10, 6 CD changer) just to hear it, now i can listen at volume "11", now i can hear wind noise and the blower motor that is starting to go out again :laugh:
 

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I run 185/60's on all four corners...............
There WILL be an occasional rub on the fronts when going over some bumps, but for the most part.....no problem.
I have been running these for 6+ years :D
 

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185/55R15 on my 2009 451.

General HP's, very pleased.

New version is here,
General*AltiMAX RT43 (H- or V-Speed Rated)
i got them on saturday, in 185/60R15's very pleased with them. yesterday we got 6 inches of snow and my car handled like it had snow tires or that there wasn't several inches of snow on the ground, no wheel spin or slippage! (my ABS/ESP has been AWOL for 5+ years). along with being quieter and smoother, should have got these instead of the lousy Kumho's in the first place, just to save maybe $50-60!
 

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Hello,

I have a 2012 Passion and looking to buy 4 new tires. I currently have 165/15 front and 185/15 rear. What is the best size for a smoother ride? I am looking to stay with 15 inch rims.
The best size for a smooth ride is a 155/65R15 front tyre fitted to a 3.5" rim and a 165/60R15 rear tyre fitted to a 4" rim. Continental make matching winter tyres in both these sizes. You can run the latest Continental winter tyres all year round, as long as you don't overheat them in the summer by driving too fast.

For the smoothest ride you need to fit any given tyre size to the narrowest allowable rim. Also make sure the tyres don't have rim protectors built into the sidewalls as these will make the ride harder. Rim protectors are extra thick rubber moulded into the sidewalls. These make the sidewalls stiff and hence give a harder ride.

However, if you want to keep the standard 5.5" rear rims and 4.5" front rims, fitting 185/55R15 rear tyres and 165/60R15 front tyres will give a smoother ride than the standard 175/55R15 and 155/60R15 tyres. This is because the wider tyres are fitted to relatively narrower rims and have higher sidewalls, which makes the tyre sidewalls flex more easily when going over bumps.

If fitting 185/55R15 tyres, run 29psi to 32psi tyre pressures. You don't need to run the air pressure of 185/55R15 tyres as hard as 175/55R15 tyres as they have a higher load index. ie. The 185/55R15 tyre will support more weight than the 175/55R15 tyre at the same air pressure.
 

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For the smoothest ride you need to fit any given tyre size to the narrowest allowable rim. Also make sure the tyres don't have rim protectors built into the sidewalls as these will make the ride harder. Rim protectors are extra thick rubber moulded into the sidewalls. These make the sidewalls stiff and hence give a harder ride.
I do not recommend fitting narrower than stock wheels onto a 451. For what gains you get in comfort, you can make handling and emergency maneuvers into a mess.

Then, if one happens to use car washes that have tracks, forgoing wheel protectors will lead to mangled wheels after your first wash. I know that from experience.

Honestly, a vastly better option is 185/60/15 on all corners. You get improved handling, improved highway performance, better treadwear, a happy ESP system, and they're significantly better than the stock sizes at soaking bumps.
 

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...if one happens to use car washes that have tracks, forgoing wheel protectors will lead to mangled wheels after your first wash. I know that from experience.
The sidewalls bulge out when fitting a tyre to the narrowest allowable rim. This protects the wheel from kerbing damage far better than extra rubber moulded into the sidewalls.

Honestly, a vastly better option is 185/60/15 on all corners. You get improved handling, improved highway performance, better treadwear, a happy ESP system, and they're significantly better than the stock sizes at soaking bumps.
185/60R15 tyres have a 603mm outside diameter. The standard 175/55R15 rear tyres have a 573.5mm outside diameter. By fitting 185/60R15 rear tyres instead of 175/55R15 rear tyres, you are raising your gearing by over 5%. This is a very big change and as well as reducing your car's top gear acceleration and possibly making your speedometer underread, it raises the car's center of gravity by almost 15mm.

A disadvantage to running the same size tyres front and back is that the car is relying on the car's electronics to prevent it loosing the back end in wet and slippery conditions especially in emergency and sudden accident avoidance maneuvers. The ForTwo is a very short wheelbase car, and you need to consider the handling characteristics on the limit. One unfortunate ForTwo owner fitted the same size tyres all round and during an emergency maneuver in wet and slippery conditions lost his back end. The car hit a brick wall and was a write off.

In dry conditions there are no such problems, as the car's front suspension camber causes the front end to break away first ie. understeer. Understeer in the ForTwo is safe, oversteer is not.
 

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Been driving for a few years now with same size tires front and rear, (on my third smart) and in all road conditions from dry to 10 inches of snow, and enough water on the road to hydroplane, Traction control cuts in before I realize I am on black ice at times and I have not had any problems with running same size tires on aftermarket (wider) rims. If you are talking racing or off road conditions, that is completely different story. As for the car that hit the wall, it is possible the driver could have contributed some error and not completely the car's fault.

Curbs in my city are high. High enough to damage rims on most cars and trucks. A sidewall sticking out from using too narrow of a rim will surely get chewed through in a short order. All tires have a min and max rim width size. If you stay within the parameters, you should be fine. I run 185\60\15 on all 4 corners, with 6.5 wide rims. Much smoother ride and better handling in strong winds.

Plus the 185 tires are more common which gives a wider selection and better price. Stock tires only come in 1 or 2 brands.
 

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The sidewalls bulge out when fitting a tyre to the narrowest allowable rim. This protects the wheel from kerbing damage far better than extra rubber moulded into the sidewalls.


185/60R15 tyres have a 603mm outside diameter. The standard 175/55R15 rear tyres have a 573.5mm outside diameter. By fitting 185/60R15 rear tyres instead of 175/55R15 rear tyres, you are raising your gearing by over 5%. This is a very big change and as well as reducing your car's top gear acceleration and possibly making your speedometer underread, it raises the car's center of gravity by almost 15mm.

A disadvantage to running the same size tyres front and back is that the car is relying on the car's electronics to prevent it loosing the back end in wet and slippery conditions especially in emergency and sudden accident avoidance maneuvers. The ForTwo is a very short wheelbase car, and you need to consider the handling characteristics on the limit. One unfortunate ForTwo owner fitted the same size tyres all round and during an emergency maneuver in wet and slippery conditions lost his back end. The car hit a brick wall and was a write off.

In dry conditions there are no such problems, as the car's front suspension camber causes the front end to break away first ie. understeer. Understeer in the ForTwo is safe, oversteer is not.
It seems our differences may be more geographical?

My Genius Wheels (bought from another SCoA member) came with oversized snows that bulged around the wheels, that certainly didn't stop the tracks of the local car wash from mangling the wheels as the sidewalls were just too soft. I'm not sure how automatic car washes work where you live, however where I am they are often built to handle big American trucks and vans. So when you get a tiny car in there like a smart, the conveyor will often force the wheel into the side of the tracks. In my case, the Blizzaks had a sidewall that was too soft to protect the wheels. My wheels never got nicked on the factory Contis. Certainly enough, when I ditched the snows for all seasons with molded wheel protectors, the damage to the wheels stopped.

For gearing and the speedometer: Going 185/60/15 vastly improves speedometer accuracy in US spec 451s. From the factory, a US spec 451 will commonly read 3-5 mph faster than actual. Mine read 4 mph faster than actual with the factory wheels and Continentals. When I switched to the 185/60/15 Vredestein Quatrac 5s (not a super common brand in the US, btw), my speedometer began reading on the dot correct. And sure, acceleration past 75 mph or so is slightly slower than stock, but the car still reaches top speed without running out of breath, so I don't really care.

As for that disadvantage for running the same sizes...I'd say that's largely subjective. Personally, I hated how the staggered set up induced oversteer while performing maneuvers that were well within my skill and the car's abilities had it been equipped with better rubber. I've never lost my rear end doing an emergency maneuver in any condition, and I've had to avoid everything from animals to a distracted truck driver. My car has spent most of its life with 195/50/15s and I don't regret it one bit. Heavy understeer was something I've always disliked about stock smarts. My equal set up made the car's handling shine.

I mainly went for 185/60/15 for the ground clearance, however the better comfort, stronger sidewalls for towing (helps a ton with 1,000 pound trailers), and more accurate speedometer were selling points. The extra ground clearance also allows me to take my car down some fun dirt trails. I can't wait to get my lift kit parts installed so I can feel more confident about more challenging trails. :)
 

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I think you meant the speedometer reads faster speed than the car is traveling. the 185's made the actual speed and the read out on the speedometer more closely matched.

As always, any modification on any vehicle should only be done with a clear understanding of what it will affect, both positive and negative. and is done at your own risk. The factory specs are for a wide range of conditions. changing items to meet your local conditions or driving is purely up to the person doing the driving.
 
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