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98 forester
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Discussion Starter #1
Ive Put on some new tires/ rims 225/35/18. I know the profile is very small but I got a great deal on these. The problem is if anything goes wrong most mechanics refuse to mess with it since this profile is under the load requirement for the Forester. I had a few places that refused to mount it for me or sell me a replacement tire for these once they found out it was for a forester. Anyone want to share any experiences good or bad concerning very low profile on the Forester? Also any discussion on tire load requirement would be great since im not sure it really concerns me that much. thanks
 

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2008 FSXT M/T
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4,170 Posts
wow your speedo is going to be waaaay off. how good of a deal did you get to warrant the complete wrong size tire for a car thats driven daily? sometimes pinching pennies doesnt pay off in the end...

i dont think its a load problem, but your rims are going to hate you if you hit any large potholes!
 

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98 forester
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26 Posts
Discussion Starter #3
Ya so tell me about eh speedo because it seems to be in touch in terms of corresponding rpms as before. I got rims and yokohama prada tires for 240$. not bad for 18s with tires. It doesnt really look that off actually. Theyre white and the subaru black so it actually has a nice look. Ill post pics this weekend after I detail and clean up. Heres a teaser I guess:

22231_778366949322_9128400_43835942_637481_n.jpg

22231_778366664892_9128400_43835940_3046749_n.jpg
 

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2008 Forester AE
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1,726 Posts
:biggrin:


compared to 225/55-17 you are almost 10% too fast, speedo [email protected] mph..
burn those off there and get some proper tires..

oh and as for load ratings, once you stray from recommended you are pretty much on your own; ie you shouldn't unless you understand the risks of what you are doing.. <-coming from someone who shops for westfalia 14in load class D tires :icon_sad:
 

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98 forester
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26 Posts
Discussion Starter #5
Ok lets be serious here. I dont drive past 80mph and sometimes have one other person in the car although im mostly by myself. Nothing in the car in terms of load except a sub which is probably 50lbs. Im not going to be risking blowing out a tire at 80mph on the highway am I?. Also the rpms are consistent with speed as it was with the original wheels. I was doing 80mph at ~ 3200rpm. The values hold with the new wheels. Im not increasing the rpms for a slower actual speed so I think the speedo issue is not actually one at all. Unless im not understanding something about this. As for lookswise, I can get away with this right? Thanks guys.
 

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2009 Forester X Premium
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3,121 Posts


One good thing I see is if you get a flat your compact donut spare will match right up :biggrin:
 

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2008 Forester AE
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I think the speed sensor reads from the transaxles, to tell the speedometer how fast you are going, ie; it doesn't know/care that you have rubber band tires on there so the speedometer and tach are going to act like normal.
The fact that everyone else is wizzing by will tell you that you aren't going as fast as you think you are, or you could use a GPS to check..

as for load index go here and see what your sidewall says; Load index

foz is ~3100lbs: divided by 4 tires = around 775lbs each corner..
this is pretty general, weight balance isn't actually 50/50 but you get the idea.

now here is where your comfort levels come into play.. each tire is carrying that amount sitting still, but it transfers around during cornering/acceleration/deceleration, plus added loads change that amount.. tires are built with a max load and it is probably not wise to be running anywhere near it. Tire age/condition/inflation will affect its limits as well.

have I ever run underrated tire? yes,
would I do it with family in the car? no, it's not worth it.
your call.
 

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98 forester
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26 Posts
Discussion Starter #10
Ok so I ran past a school zone and the visual radar thing clocked me at 39 when my speedo was ~45 so there is a little difference I guess. Anyways, it will look pretty when im done washing and detailing. Come on someone tell me its badass or something haha.
 

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2007 Forester 2.5x SE
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Ok so I ran past a school zone and the visual radar thing clocked me at 39 when my speedo was ~45 so there is a little difference I guess.
Yeah that is about 10% difference, like previously mentioned. It will also affect/lower your MPG.

Try putting the Stock (OEM) size tire and your tire in this size calculator.

Anyways, it will look pretty when im done washing and detailing. Come on someone tell me its badass or something haha.
Can you show some pics of the whole car? Then I can say if it is bad ***. The photo you have is basically a crop of the wheel, and at a awkward angle. I can't get a feel for how the wheels look on the Forester, or measure its Badass'ness.

What is the Load rating of those tires anyways??? I have never heard of a tire dealer not installing a tire because of the load rating (not that I have tried), but I have had tire shops tell me that they will refuse to put on anything but the EXACT original OEM size. They wouldn't even do a tire with the same outside Diameter, if the width was different from stock.

Bad *** or not, I'd say that because you are running such a short side wall, with a tire that is not made to handing the load of the Forester, it could be a serious safety hazard. Especially if you hit a Pot Hole, you only have about 3" of side wall, you are likely to get a pinch flat in the side or mangle your rims. Also in hard corners, when most of the weigh of the vehicle shifts to one tire, there is a higher chance of a blow out. To top it off, if you are in an accident, and the insurance company finds that you are running on unsafe tires, there could be a problem. If you don't load up your Forester, can avoid all Pot Holes and take your corners easy, you should be fine.
 

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98 forester
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Discussion Starter #15
Ya thanks for all the support guys. Im not sure what the load rating is on these tires, but as we figured out above its going to be less than 775lbs max load I guess. Im not sure I understand why the rpms are the same with both sets of tires though, considering the speed is "off" in terms of the meter. It seems to be lining up with what the spedometer reads regardless... I would love to hear from people who have had problems or lack of any problems with using low profile daily. As for pictures I am doing a good amount of detailing work and some dynamating this weekend I will post pics of the clean product. Ive been waiting on a friend for a quality camera as well since these pics ive taken are from a decent phone which is never as good(even with the 5 mp it claims to put out).
 

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Ya thanks for all the support guys. Im not sure what the load rating is on these tires, but as we figured out above its going to be less than 775lbs max load I guess. Im not sure I understand why the rpms are the same with both sets of tires though, considering the speed is "off" in terms of the meter. It seems to be lining up with what the spedometer reads regardless... I would love to hear from people who have had problems or lack of any problems with using low profile daily. As for pictures I am doing a good amount of detailing work and some dynamating this weekend I will post pics of the clean product. Ive been waiting on a friend for a quality camera as well since these pics ive taken are from a decent phone which is never as good(even with the 5 mp it claims to put out).
Your engine is still spinning the same, and the hub is still turning at the same rate, but the tire is smaller circumference. For each rotation of the tire you're going a shorter distance. The car has no idea how big your tires are, the speedo is calibrated approximately for the stock size tires (even those read a little bit off your real speed). The speedo is dead on with 215/65/16 tires, your tires are over 2 inches smaller.
 

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98 forester
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Discussion Starter #18
and so actually thats a bad thing, especially on a car with 216,000 miles on it...
 

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2008 Forester AE
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you may notice it feeling a little more peppy off the start but get it up to speed and the revs will be higer than normal..

but it's not going to hurt anything, it just looks a little funny until you get the proper size. er.. I mean badass.. :biggrin:
 

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and so actually thats a bad thing, especially on a car with 216,000 miles on it...
Yeah, the odometer is going to read many more miles than you're actually putting on it. When I had the undersized tires on I usually just used my GPS for speed when on the highway.
 
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