Wider tires on stock rims?

Discussion in 'Prime Accessories and Modifications' started by Krzysiek_KTA, Aug 21, 2017.

  1. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    Just lame question.
    Will Prime's stock rims accept wider tire?
    Will 215/65 R15 tire be doable replacement for stock 195/65 R15?
     
  2. ct89

    ct89 Active Member

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    If you go with wider, you should lower the aspect ratio to keep the diameter the same.

    The closest equivalent diameter with a 215 width, you would want a 60 aspect on a 15" rim.
    A 215/60/15 would be 0.8% larger diameter so your speedometer readings would be about 1/2 MPH low at 60 MPH

    At some point, the width becomes a problem where the tire can rub on the fender or inside the wheel well when you turn but I think 215 should be pretty safe.

    I run my 2010 Prius on 205/55/16 and they seem to have plenty of margin. I also really like the look of 55 aspect tires. Much nicer than the stock 65s. I don't find anything below 50 to be aesthetically pleasing (personal opinion).
     
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  3. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    THX for info
     
  4. GrGramps

    GrGramps Active Member

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    I would be concerned that a tire wider than the rim was designed to accept would experience distortion in the tread area. This, in turn, could affect traction and wear characteristics.

    I am not a tire engineer, so I'm interested to see what others think.
     
  5. ct89

    ct89 Active Member

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  6. jaqueh

    jaqueh Active Member

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    Will these tires rub against the wheel well?
     
  7. WilDavis

    WilDavis Senior Member

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    I have a set of 205/50R16s on the OEM alloy rims on my Gen II (touring) and have not found any problems with the handling or wear. My winter wheels are 15" steel rims shod with 185/65R15 snow tyres, no problems to report there, either!
     
  8. OptimalPrime

    OptimalPrime Junior Member

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    I'm a bit torn on both tire-size selection and ground clearance on this car......just as I was on my 2005 until I found a great solution for it. Unfortunately, the solution for the 2005 isn't the same as for the Prime.

    On the Prime, I'm considering putting larger-diameter tires on it, and probably will. But probably not until I'm through one set of specified-size tires during warranty. Toyota would try to blame any drivetrain problem on improper tire size. So for now, just running at max-sidewall psi will be all I can do about ground clearance, unless I go to some sort of minor suspension lift, spring helpers/bumpers, or whatever.

    On the 2005, standard size was 185/65R15, and I found that upsizing to the 195/65R15 used on 2010+, works GREAT. Yes, it is a larger diameter, and yes it affects speedometer and odometer. But so what? When the speedo says 46, I'm going 47. When it says 70, I'm going 71.5. Not exactly a problem, not exactly destroying the car due to a crazy final-drive ratio. It also raised the ground clearance by 6.5mm (just over 1/4 inch....not a huge deal, but I'll take it....New England winters can use some extra ground clearance). Another advantage was that it made my wheels and tires interchangeable with those of friends who own Gen III and PIP....and now my own new Prime. Between us, we have extra wheels/tires which could be borrowed in emergencies instead of riding on donuts, etc. The final advantage was from choosing Michelin X-Ice3 tires, which have an XL load rating while still having T speed rating. 95T is a much higher load rating, plus a higher speed rating, than the 89S rating of the Toyos on my Prime.

    As for the Prime........for now I am going to put a new set of the 195/65R15 95T X-Ice3 on it within a few days, as soon as I can get an installation appointment at BJs, where I actually bought the tires several days ago when two combinable coupons were expiring, before I even bought the Prime. The tires just arrived there, after I bought the Prime. Had I not bought the Prime, I would have put them on my 2005. Now with them going on the Prime, and the 2005 becoming either a "backup/work" car or being sold, I'll just put partially-used tires on it, or grab yet another set of tires during the next good tire sale. On sale, I paid $300 for the 4 tires, and $30 for installation, etc. An outright steal.

    Why put snow tires on, when it's not winter? Because they are GREAT tires year-round! I have about 40K on them, and only the fronts are essentially done. I never rotate tires except as they near end of life, if I want to make them wear out at the same time or last until a particular season. The rears still had half tread, so that implies a set lasts 53K miles. So running them year round is easier than even swapping mounted sets twice a year. Cheaper too, if you value your time at all. I rotated the half-worn rears to the front before driving 5555 miles on my eclipse expedition last month. Including entire days cruising I-80 through NE/WY at 84mph. And going over Teton Pass between Jackson Hole and Grand Targhee via Idaho, several times. I've not been left behind by any car on any ramp, not only on that trip, but anytime I've owned the tires. A Maxima made a good run at getting away on a straight section once, but I got back to him on the final ramp curve before letting him blast off into triple digits. Max sidewall psi is 51psi, and I run 50psi at all four corners. It's like the car is on rails.

    Last reason I like the X-Ice3 is the almost total lack of mpg penalty, which surprised me greatly. One summer on Ecopias, my best full tank was 72.7mpg; the next summer on X-Ice3, it was also 72+. Maybe I was driving better, but going 500 miles of routine but careful everyday driving at 72mpg on snows in a Gen II at legal tire pressures, proves to me that it's not worth switching tires twice a year.

    The Prime has a HUGE AMOUNT OF EXTRA SPACE in the wheel wells, in comparison to what the 2005 had before I slightly increased tire size. I'm definitely trying sticking with 15 inch wheels, not the least bit interested in larger wheels unless I find I can get the optimal tire diameter increase only by increasing wheel size also. Low cost (using wheels I already have; and cheaper tires), added pothole protection, and keeping my wheels interchangeable between all the generations of Prius which my friends and I have, are good reasons for staying with 15 inch. I'm thinking 195/70R15 would have no problems with fitting and not rubbing, etc. That would add 9.75mm of ground clearance. Or even 205/70R15, which would add a total of 16.75mm ground clearance. Not sure if I'd consider 215/70R15 but the rise would be 23.75mm, almost an inch of lift, and I think the car could use that much when you see a snowplow-thrown block of ice in your lane! I'm not crazy about going to 70 series vs 65 handling-wise, but it does gain ground clearance without the tires getting too fat (which could cause rubbing, and definitely causes mpg loss, worse hydroplaning, greater cost, etc). I can remember when 70 series aspect ratio was considered low-profile and great handling (in the 1970s) and that was when max inflation pressures were 32-36 psi rather than 44-51psi. I'm thinking a 70 series at 50psi will meet my handling needs, and it will have awesome load rating and pothole protection.
     
  9. WilDavis

    WilDavis Senior Member

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    The problem with leaving the winter tyres on year round is that they will wear out very quickly, especially if we have another summer like 2017. The rubber used for winter tyres is much softer and so is much more effective with snow and ice! I've found that the Bridgestone Blizzaks I have on my winter wheels are fantastic in the wet, but there's no way I would leave them on through the summer. I put the original 16" OEM rims shod with inexpensive summer tyres on the car at the end of April, and Blizzaks on a set of steel rims for the winter at the end of October. Oh, and by the way, "All Season tyres" are a compromise, i.e. jack-of-all-trades, master-of-none! ;)
     
  10. ct89

    ct89 Active Member

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    I too endure NewEngland winters and 100% agree that snow tires are the best choice winter driving. Not as good as AWD but a significant improvement over normal all-season tires. I've used several different brands and have observed both increased tire noise and a loss of ~3 mpg when I switch to the winter tires. Sadly this usually happens when they switch to winter gas and the temperature drops which also seems to reduce my MPG by another 3 mpg. For winter NewEngland driving, I have no question winter tires are a good trade-off.

    My favorite tire size for the Prius is 205/55/16...I like the look of 55 ratio tires and slightly larger rims.

    With my 2004 Prius, the issue was more a case of the OEM 185/65/15 just being the wrong size. The speedometer was off. Somewhere in the Gen2 forum is a long discussion about this and what I consider clear evidence that the 195/65/15 was the size the car was made for but the theory was that Toyota went with the smaller tires in the US to try and squeeze (cheat) an extra MPG or two out of the ratings. As I recall 195/65/15 was stock in some countries and when I switched to them, the speedometer became perfectly accurate, I observed no loss of mpg and better handling which was probably more due to putting good tires on the car rather than the originals which barely made it 30K miles.

    With the prime, the stock 195/65/15 seems to be correct size. This is a 25" diameter tire. If you want to upsize the rims, 205/55/16 and 205/50/17 are within 0.1" of the 25" diameter and will have less than half a percent impact on the actual speed of the vehicle. Far less than the difference in diameter between new and somewhat older tires. If you want to stick with stock rims (as the title suggests), a 205/50/15 will fit and comes in at 24.7" diameter which is only 1% slow.

    For NewEngland winters, there is a debate around whether narrower tires are better for snow as they slice through easier or if wider tires are better for ice as they have a slightly larger footprint. I've driven the 205 width for many years and like the look/feel but doubt there is really much actual difference to the 195's. I personally wouldn't try to go narrower (185's) or wider (215's) although I agree with a previous poster that there appears to be a good bit of room.

    As for the question of running snow tires in the summer, I have never tried that. For the cost of a set of decent alloy rims ($200-$300 at most on craigslist) I have separate summer and winter wheels. A floor jack and a cordless impact driver and they can be swapped in about a half hour. AND as a bonus, the "other set" is now a bunch of full-size spares for the prime should I have a flat. I'll just need to hitch a ride (spouse, uber, etc.) to my garage to grab one should I get a flat.

    You pay for rubber by the mile. I don't think having a winter set in the winter costs extra in the long run as both sets just last longer...OK, maybe slightly more as winter rubber is a bit softer. I use Michelin defenders in the summer and well exceeded 80K miles over their 7 year life. I think the winter tires usually go about 5 seasons before I decide I want more tread depth but I'm only putting maybe 8K on the car between sometime in November and sometime in April when I do the switching.

    I have never used the X-ice tires but was planning on grabbing a set for the Prime when Costco has their sale. The winter tires from the 2004 Prius I traded-in were at the end of their life and need replacing anyhow. If others have experiences with particular brands of winter tires on Prius' I would love to hear about them. I had no issues with a set of Altimax tires on my 2010 Prius and the Toyo G02 Observe's were great on the 2004 Prius. I also had a set of Firestone Winterforce on the old '89 all-trac Camry and you couldn't make that car slip in the snow if you tried. Blizzaks, X-Ice and Hakkapeliitta's are on my list to eventually try.
     
  11. OptimalPrime

    OptimalPrime Junior Member

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    I totally agreed with what ct89 wrote above, when I bought 5 extra Gen II rims at a junkyard (plus 4 more for a friend) for about $50ea to keep winter and summer sets mounted. My 2005 is ideal for this set swapping, not having to deal with the "fewer than 8 TPMS sensors can be entered into a Gen II computer" problem which set-swappers run into in later years.

    ct89 is also totally right about cost per mile not being affected by how many sets of tires you have, and that in fact seeing as winter tires generally have a higher cost per mile, you can use that to help justify the cost of the extra set of wheels. And it's true that it gives you 4 mounted spares! Yet, the costs (even if you do it yourself "for free") of swapping sets twice per year must be considered. I have better things to do than swap tire sets, when the winter set already on the car is awesome during all 4 seasons. Do it because it's what you want to do, but don't do it for "savings" unless you don't value your time. True whether you do it yourself or take it to a tire shop.

    Does the Prime support 8 or more TPMS sensors being recognized? I haven't checked yet, but it's a major downside of swapping sets on Gen II and Gen III with TPMS. If fewer than 8 are supported, have fun either getting it reprogrammed twice a year or taping over the warning light half the year. Personally I'm hoping that at least 9 are supported, for 2 sets and a spare. Anything less is just a ripoff to generate service business for dealers.

    Anyway, I mounted X-Ice3 on my existing wheels and planned to mount summer tires on the new junkyard set. But I never could bring myself to go back to any other tire, even in summer. It's simply a superior tire to the original Ecopias, which I had used up a near-new set of already. Could I find a superior summer tire too? Sure, but why bother? The X-Ice3 does everything I ask it to, and I ask a lot of my tires both in terms of load and cornering.

    Maybe I'm odd, but the other reason I decided against swapping summer/winter sets (even after having the extra set of Prius alloys in hand) unless necessary to get the performance I want, is that I also lean toward not rotating tires at all. Once a tire is on a specific wheel on a specific location on the car, and working well, I simply like leaving it there. If it gets out of alignment or has some other problem, I get to see it in the treadwear pattern, and can diagnose the problem. If you rotate religiously, every (or just "both" for unidirectional-tire front-back rotation) tire contains the sum of several wear patterns all mushed together, and you don't know which corner of the car has which of the possibly several problems adding up to what you see. Also, I'd be more likely to rotate tires if I haven't seen plenty of cars where simply removing a wheel and putting the same wheel back on the same place (especially if not marking the wheel and a wheel stud to put the same studs through the same holes), slightly moves the brake rotor relative to the caliper, essentially making the brake pads trace their circle on a slightly different center of rotation on the rotor. Rub, rub, rub. This is because the rotor isn't completely located by something fixed like just the wheel bearing.....if's often able to shift around until you tighten down the lug nuts. In some cases, bevels on the wheel-nut holes locate the rotor. In other cases, it's worse than that: you can move the rotor around within the slop tolerance of the rotor holes the studs pass through. In other even worse cases, you're able to move the wheel a bit before tightening the nuts down, due to slop in the wheel holes, conflicting holes/bevels, etc. So you're able to change the brake-pad track without even changing which stud is in which hole. Often it also depends on which nut(s) you tighten down first. So I like leaving things where they are whenever possible.

    As a mechanical engineer, I find it especially criminal how car manufacturers specify marginal tires, and/or the lowest safe inflation pressures as the recommended pressures. What they basically do is spec a tire which just barely carries the load (with the required safety margin) at their specified inflation pressure, giving the softest possible ride and lowest tire cost without them being sued for selling death on wheels. Toyota is not the worst offender at this. The owner's manual for my girlfriend's BMW goes so far as to specify such marginal load ratings and inflation pressures, that the owner's manual tells you that you have to inflate to a different, higher pressure if you actually put 5 people in the car, and/or if you plan to go over a certain speed (85mph I think). Totally ridiculous on a car that also happens to specify high speed tires (130mph or 149mph, I forget), even before considering what happens when a few psi leaks out. Are you supposed to call a tow truck, drive unsafely, or inflate it roadside when your TPMS light comes on? Don't get me going........
     
  12. OptimalPrime

    OptimalPrime Junior Member

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    Well......I changed my mind and did what I wanted to, rather than worry that a small change in tire size might cause Toyota to go nuts on me if there's ever a warranty issue. So I put the new set of 195/65R15 X-Ice3 onto the 2005 instead of the Prime.

    But the real news is that I put a set of 205/65R15 X-Ice3 onto the Prime. I'm happy with the result on both cars. No surprise, as the concept was proven by my previous set on the 2005.

    The new set for the 2005 went onto my spare set of Gen II rims, so that I have the entire worn set remaining mounted as spares. I've hung one on the wall in my garage, and stored one at my business also. And of course there's a donut spare in the 2005 also. So if I ever have a flat on the Prime that the flat kit and compressor don't handle, I just have to get the Prime to either home or to work. Or to get myself wherever the 2005 is (typically home, if I'm in the Prime) to be back in business.

    I'll post pics of the Prime with the bigger tires here, annotated with some details.

    20565R15XL99T_onPrime-20171006annotated.jpg

    Two of the three Prii that I've owned......the 2001 which I bought 17 years ago this month, was sold when it was 2 years old.

    Both are raised 6.5mm by putting on tires 10mm wider than stock. Just a little beefier looking, just a little better ground clearance, and a lot more safety margin on load rating, potholes, etc.


    20565R15XL99T_front-20171006annotated.jpg

    I don't think it looks too abnormal, in fact it fits the wheel well better than stock IMHO.

    20565R15XL99T_rear-20171006annotated.jpg

    Well, here's a partial answer about wider tires on stock wheels for Prime. I think these 205s look excellent, but I'm sure the boy-racer types who live where it never snows, will think they look too much like monster-truck tires and not enough like low-rider tires. I'd lean toward not trying 215s on these wheels even if the specs say it's OK. I'm thinking that while 215s might stay safely mounted, you might get more of a bulgy-donut look than you'd want.


    Soon, I'll post in the for-sale section, the two spares on Gen II wheels that I no longer need, plus an extra Gen II wheel that is also surplus to my needs at the moment with spares everywhere and no desire to mount two sets of tires for seasonal use. As the spares are almost down to the treadwear indicators, their diameter is about that of a Gen II 185/65 stock tire, yet they are also genuinely 195/65 tires which are actually specified on Gen 3, Gen 4, and Prime. Basically, a mostly-worn Gen3/PiP/4/Prime tire is suitable for use as a spare on all of those, plus Gen 2.
     
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