idosubaru Posted October 3, 2011 Share Posted October 3, 2011 1996 Legacy LSi with stock 5 spoke aluminum wheels. Stock tires are 195/60/15. What are the thinnest tires I can install on those rims? I don't know the technical aspects of tires and installation. I can go down to 185 probably....can I go to 175 or is that just ludicrous? I have other 4WD Subarus, so I don't care about handling or snow performance on this vehicle. For example: I castrated it to FWD and EJ18 in lieu of the stock EJ25! Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 3, 2011 Share Posted October 3, 2011 When you get too skinny the price starts to go back up. I'd just find the skinniest tire that you want to pay for and go with that. I don't know for sure, are the aluminum wheels are any wider than steel wheels? That might make a difference. I have 185 70 14 on my sedan. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 3, 2011 Author Share Posted October 3, 2011 (edited) not paying $200 per tire but price isn't really in the picture. 185 should be doable but 175 sounds crazy, just because i've never bought any tires that skinny before? Edited October 3, 2011 by grossgary Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted October 3, 2011 Share Posted October 3, 2011 Why the interest in going to the smallest tire? Quote Link to comment Share on other sites More sharing options...
rverdoold Posted October 3, 2011 Share Posted October 3, 2011 better grip on ice and snow I assume. I was looking for 175 but could not find them in 70 high with right load marking (only 82, i want 89 or higher) so went with 185 in 65 high. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 3, 2011 Author Share Posted October 3, 2011 when you say 175's rveroold, what size wheel and what vehicle was that and do you know if the 175 would fit the rim? Why the interest in going to the smallest tire?smaller tires to ease the load on the dinky EJ18. larger wheel/tire combo's reduced mileage and performance, i'm hoping for the opposite with a size or so smaller. it's not for snow/ice traction, I have other vehicles for the rough stuff. Quote Link to comment Share on other sites More sharing options...
jarl Posted October 3, 2011 Share Posted October 3, 2011 (edited) http://customwheelsmarket.com/rimwheelwidth1.html I think the OEM alloys are 5.6 inches wide (can someone check this?) If that's the case you *should* be able to run 175s Edited October 3, 2011 by jarl Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted October 3, 2011 Share Posted October 3, 2011 when you say 175's rveroold, what size wheel and what vehicle was that and do you know if the 175 would fit the rim? smaller tires to ease the load on the dinky EJ18. larger wheel/tire combo's reduced mileage and performance, i'm hoping for the opposite with a size or so smaller. it's not for snow/ice traction, I have other vehicles for the rough stuff. I don't think you are going to gain much in running small tires for better gas mileage. A very tiny little bit, at most 1 mpg, if that. You won't save much if you are thinking there is that much savings in less rolling resistance. If it were me, I would buy the same size of tire that came with the car, and then pump them up to 2 to 5 extra pounds of air to slightly reduce their normal rolling resistance, if reduced rolling resistance is your goal. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 3, 2011 Author Share Posted October 3, 2011 i've already done the higher PSi - i do that to all my cars. I don't think you are going to gain much in running small tires for better gas mileage. A very tiny little bit, at most 1 mpg, if that. You won't save much if you are thinking there is that much savings in less rolling resistance. If it were me, I would buy the same size of tire that came with the car, and then pump them up to 2 to 5 extra pounds of air to slightly reduce their normal rolling resistance, if reduced rolling resistance is your goal.i'd rather talk about the question in the title and not discuss this. no one else is driving a heavy EJ25 vehicle swapped to EJ18, it's totally different from most other subarus. and after 60,000 miles i already know it helps: going larger than stock significantly reduces performance/mileage, it seems quite logical to presume the opposite could happen. it does fine in flatland, but i rarely drive where it's flat. the XT6 is the opposite - i get better highway mileage with larger diameter tires, but it's got way more available power. Quote Link to comment Share on other sites More sharing options...
rverdoold Posted October 3, 2011 Share Posted October 3, 2011 It would not be for the Germans to have sought this out of course!!! Oh well, unfortunately the pdf is in german. But: http://www.adac.de/_mm/pdf/Breit_oder_schmal_23603.pdf But if you look at the image at the bottom the + - and average symbols everybody understands (i hope). This is about summer tires done in 2009. Dimension is same as in english, brand does not matter all michelin. Nasse (bremsen, handling und kreis) = Wet road (braking, handling and turning) Aquaplanning (langs, quer) = aquaplanning (streight and diagonal) Trocken = dry road braking and handling Komfort (vederung) = comfort and suspending (guess lower tyre is really bad in this). Gerausch = is noise in and outside roll wiederstand = is rolling resistance They did not test the 175 but honestly I dont think there will be a huge difference with the 185, except that on wet roads you are pretty screwed. I will have to buy new tires next year and this test made me go for 195-65-15 instead of the 205-55-15 i have now. I prefer to have little more response compared to little more fuel consumption. I think it is way more important to have the right tire pressure. I run always at 2.8 bar = about 40 psi in the 205 tires. My winter tires are 185-65-14 and run on 2.5 bar = 36 PSI. I notice milage difference when tires are about 4 to 8 psi under the usual. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 3, 2011 Author Share Posted October 3, 2011 on wet roads you are screwed...what do you mean - it's more likely to hydroplane in a 175 than 185? i'm not too worried about it. like i said i have a whole fleet of subaru's to pick from, this one is not my rough weather ride. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted October 3, 2011 Share Posted October 3, 2011 (edited) car..................wheel width...........................tire width.............difference L..................... 5.5 inch (14" steel)................185 (7.28")...............132% L..................... 6.0 inch (14" alloy)................185 (7.28")...............121% LSi................... 6.0 inch (15" alloy)...............195 (7.68")...............128% GT................... 6.5 inch (16" alloy)...............205 (8.07")...............124% OBW................ 6.0 inch (15" alloy)...............205 (8.07")...............134% if you the take the smallest difference between the tire and wheel, 121%, on the L with 14" alloy wheels, and apply that to the 14 x 5.5 inch steel wheel on the ''L'' it comes in at 169 tire. that's doable. do the same to the 15 x 6 inch alloy wheel (or 15 x 6" steel from later years) and you come up with 184 tire. that's doable. 175 on a 6 inch wide wheel would give you: proposed ..........6.0" wheel.................175 (6.88") tire................ 114% not a huge ratio difference from 121%, but a difference of 5%. there is probably an industry standard ''do not go below'' figure, but you would have to ask some one (engineer) in the tire industry. my concern would be the handling and braking of the car at speed on the narrower tires. especially at high speed. you can always put enough air in the tire to make sure it holds the rim. so much of tire size is based on the fashion / style and popular wheel size of the day it is hard to know what is actually needed. Edited October 3, 2011 by johnceggleston Quote Link to comment Share on other sites More sharing options...
rverdoold Posted October 3, 2011 Share Posted October 3, 2011 (edited) You mentioned, however I think that there will be no big difference in fuel consumption between 175 and 185 or rolling resistance. The other thing is that I run 205-55-15 in summer and 185-65-14 in winter (nearly same rotation) and do only notice a little increase in winter. Which I address to colder weather. Ok I admit that it does not take in account the improved fuel consumption because of the smaller tire, but in warm winters (not freezing) it was the same, may +/- 3% max and that is for 205 to 185. Therefore my opinion about 175 to 185. I do notice that the 185 winter tires tend to slide and skid easier on wet roads (no abs) although I am comparing two complete different types of tires. I feel more confident taking a corner fast in the wet with the 205 then the 185. Edited October 3, 2011 by rverdoold Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 3, 2011 Author Share Posted October 3, 2011 i'm ready to go to 185's at least....175's seem too small...for no other reason than they aren't common to recent subarus. comparing winter/summer driving is hard. air density is different, cars run/idle more in the winter, people travel and drive different in snow/ice verses summer time, etc. interesting math, i see what you're saying. maybe i'll try 175's on the rear and see how they do. or i'll go look at them first before installing them and say "WOW, way too small" Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 4, 2011 Share Posted October 4, 2011 I see what you're getting at. You might think about going with a lower profile tire as well. If you went with a 185/60 you would get a slightly smaller overall diameter which would help put power to the road a little easier. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted October 4, 2011 Share Posted October 4, 2011 maybe, find a pair, or two, of 175s used so if if it doesn't work you're not out the full price. are 175s even available in the matching diameter? 175/70/15 is ~2% larger in diameter. 185/65/15 is ~1% larger in diameter. dropping down a size with either one would put you 1% and 2% smaller, respectively. the 185 is going to give you more choices and i think lower prices. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 4, 2011 Author Share Posted October 4, 2011 good call john, could put two 175's up front to see what happens. if they perform terribly in the rain or otherwise i can throw them away or put them on the rear for a year. i *might* put two spares in the trunk just in case. Quote Link to comment Share on other sites More sharing options...
rverdoold Posted October 4, 2011 Share Posted October 4, 2011 maybe you can find (at least here we have them) companies that deal in tires. So they recycle and sell new + second hand tires. Maybe he has something laying with matching radius in 175 so you can try. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 5, 2011 Author Share Posted October 5, 2011 yes, used tires are easy to find around here...haven't searched for that size yet but shouldn't be a big deal. Quote Link to comment Share on other sites More sharing options...
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