235/45/17's on 17x7's

[Leitnin]

so. maybe this was a bad thing to have done but i did it at the tire tech's advice and it was before i knew anything about cars really.

i have a set of 17x7 adr wheels (that i don't even remember what model) that are wrapped in 235/45/17 dayton daytona tires (yeah i know). they were on my 96 esi for a few years and have been on my 98 tsiawd for several more. now i need new tires (screw on the corner of the shoulder block)

anyway, looking at all the tires and particularly the kumho ecsta mx's i was planning to buy, the 235/45/17 has a minimum rim width of 7.5".

that made me look at min width for other tires and the 235's pretty much show 7.5 across the board.

so:

1. can i fit the 235's on my 17x7's.
2. do i want to?
3. im kindof on a budget so id rather not replace my rims.
4. what would be the optimal tire size for these 17x7's?



thanks guys

 

[jtmcinder]

I'd get 225/45/17s for 17x7s. Either MXs or Azenis, given the lack of rain in SoCal.

- Jtoby

 

[arash15]

i run 235's on 7" wide rims. its noting to get them to fit, although there will be a little bit of bulging after you put some miles on it. so far so good.

 

[95GSXBLUR]

To run 235/50/17s on my 7.5 inch rims I run 1/4" wheel spacers to make sure they don't rub. I'm lowered slightly on KYB GR2's and Eibach prokit. I don't know if anyone else has problems with rubbing, but I sure did.

 

[illeffekt vr-4]

235/45-17 should fit ok on that 17x7

have you looked into 235/40 tires?


http://boostin.home.mchsi.com/rimwidth.htm

 

[Leitnin]

running 235/40's would change the diameter more than the 225s and that seems like it would make the rim width worse in terms of being a little undersized.....minimum rim width recommended for 235/40's is 8".



well. ive had 235/45/17s on the 17x7s for years. if running 225s makes more sense that works for me. i trust you jtoby. the 225's will be a bit smaller in diameter .4" i believe. thats no big deal i guess.

do you think if i got the 235/45/17s and then when i could afford it got a set of 17x8's that would be worth while or should i just get the 225s and if i end up with 17x8's they would probably be 16x8's anyway right

just don't want to make a mistake with a 500+ dollar venture.

jtoby, if with a set of 17x7's on a street car youd go 225/45/17 mx's just confirm that for me and i'll do it. if you think its worth getting the 235's and making them fit (seeing as it seems like they will) then i'll do that. you know more about suspensions than anyone else i know, so there you go. just tell me what to do (which you already did)

 

[wret]

Here's a recent discussion on tire width vs. wheel width.

http://dsmtuners.com/forums/showthread.php?t=231889

 

[jtmcinder]

jtoby, if with a set of 17x7's on a street car youd go 225/45/17 mx's just confirm that for me and i'll do it.

While I'm not sure if I want to take responsibility for this, if forced to run 17x7s, this is what I'd do if I lived in SoCal. If I was forced to run these wheels in a part of country where it rains, then it would be SPTs, instead.

- Jtoby

 

[TSIMonsteR]

I read wret's entire tech article and it helped alot. I just cant decide between 225/45/17 or 225/50/17 for the stock GSX Wheel (17x6.5)

The tires will either be Exclaim UHP or SPTs, but 50 or 45?

Car is stock height and will never be lowered more then .5"

 

[wret]

Thanks for reminding me, I gotta update that thing one of these days.

You'ld probably not have a problem with the 225/50/17's but go with the 225/45/17's. They are very close to stock diameter.

 

[TSIMonsteR]

I said 225 (I don't know why), but I meant 215. Would 225s bulge too much on the 6.5" rim? I plan to AutoX quite a bit, so I want the best corning I can get. I have heard say "Sure, 225 on the stock rim is the way to go" While others say "225s will bulge to much and hurt your overall performance more then help"

Tire sizing is still confusing to me. I guess I could try to 225/45 or the 215/50 and see which I like best...

 

[Slow99x]

The 235/45R17 is closer to 215/50R17 in diameter than the 225/45R17.

The simple formula: Tread width (215) multiplied by aspect ratio (.50) times 2 times .0396 plus rim diameter (17) =25.514
235x.45x2x.0396+17= 25.3754
225x.45x2x.0396+17= 25.019
205x.55x2x.0396+16= 24.9298

Best sizing for a late model GSX is the 235/45R17
Best sizing for early model GSX, late and early GS-T, all 1g is 225/45R17

 

[wret]

Well, I don't think General makes the Exclaim in 215/50/17, so that may make your decission easier. You are right; most 225/45/17's are not rated for 6.5" wheels, but neither are the Exclaim 215/50/17's.

 

[Cesar]

The 235/45R17 is closer to 215/50R17 in diameter than the 225/45R17.

The simple formula: Tread width (215) multiplied by aspect ratio (.50) times 2 times .0396 plus rim diameter (17) =25.514
235x.45x2x.0396+17= 25.3754
225x.45x2x.0396+17= 25.019
205x.55x2x.0396+16= 24.9298

Best sizing for a late model GSX is the 235/45R17
Best sizing for early model GSX, late and early GS-T, all 1g is 225/45R17

Are you able to tell me the difference between the late model and early model gsx?

Thanks

 

[Slow99x]

Early model GSX/TSI came with 16" rims. The speedo was calibrated for this size.

 

[jtmcinder]

Yes, some 2Gs came on 205/55/16s while others came on 215/50/17s, but how sure are you that the speedo gear is different?

- Jtoby

 

[Slow99x]

Test it. Drive past one of those police radar signs. You know the ones. They have the posted limit and how fast you are actualy going. If you have the wrong size of tire on the car, your speedo and the sign will read a little different. Maybe only a couple of miles per hour off but still different. I drove past one with my 215/50R17 and I was dead on. My friend drove past the same one and was a little off. My car is a 99 and his is a 95. If I'm wrong then you should be able to sue Mitsubishi for any speeding tickets that you have recieved for having an inaccurate speedo.

 

[jtmcinder]

That's a really silly answer, given how inaccuate our speedos are known to be. And, of course, if I change my tire size, my speed will change for a given RPM and gear.

My question was really quite simple: are you sure that the 2Gs that came on different-sized tires have different speedo gears?

What's the point to this, you ask. Well, if they used the same gear for all 2Gs, then people should stop getting so worked up about 225/45/17 vs 235/45/17, etc., at least with regard to the speedo. Getting worked up about the added torque with the 225s would still be quite cool.

- Jtoby

 

[Pro3racer]

Not to hyjack the thread, but i'm trying to understand these min's and max's. I have 6.5" wide wheels, and 225's no there right now, will 225/45/16 be fine for this? These will be my autocross/lapping day wheels and tires.

 

[Slow99x]

To answer the question, no. I have not measured the speedo gear. I have not compared part numbers. The only thing I can base this on is a personal experience. The reason that I even mention the experience is due to my friend noticing how accurate my speedo was when I let him drive the car as we went past one of these radar signs. To test the theory we drove his car past the sign and there was a different result. When you mention how innacurate our speedometers are, speak for yourself because mine is dead nuts on. It doesn't matter what gear or rpm, it is very accurate. If a vehicle manufacturer did not make an accurate speedometer they could be taken to court for various liabilty claims.

 

[Slow99x]

Not to hyjack the thread, but i'm trying to understand these min's and max's. I have 6.5" wide wheels, and 225's no there right now, will 225/45/16 be fine for this? These will be my autocross/lapping day wheels and tires.

Michelin provides a MAST Fitment Guide to all of it's distributors and contains this information of which tire width and aspect ratio require what min/max rim width. Contact your local distrubutor and ask them to see this guide. I had no problem looking up this info for a customer when I worked for NTB. Being that I delt with so many cars and different sizes, I didn't take the time to memorize that info.

 

[jtmcinder]

If a vehicle manufacturer did not make an accurate speedometer they could be taken to court for various liabilty claims.

The hole is getting deeper.

Please show me a law that requires the speedometer to be accurate. I'll give you a headstart by providing a link to federal Title 49, which has no requirement for this at all.

http://www.nhtsa.dot.gov/nhtsa/Cfc_title49/

That leaves you the states and I'll do you a favor and rule one out. In my state, the requirement is that the needle move when the car does. You can request a better test after getting a ticket, but there's no requirement that your speedo be accurate in PA, which is good, since I rarely drive on tires as large in diameter as stock.

Going farther, please note that many complaints have been filed against Mitsubishi by, for example, people who leased a car. The known over-estimate of actual speed is replicated by the odometer, making these people pay more, since the odometer reads higher than the actual distance travelled.

Finally, it might not surprise you to learn that rental companies prefer cars with positive error. Chevy Malibus, for example, also over-estimate speed and distance by around 5%. The companies initially deny this, of course, but when pushed claim that they are doing the customer a favor by reducing the chance of getting a ticket in an unfamiliar car.

- Jtoby

 

[4BangR-x]

Not to hyjack the thread, but i'm trying to understand these min's and max's. I have 6.5" wide wheels, and 225's no there right now, will 225/45/16 be fine for this? These will be my autocross/lapping day wheels and tires.

Minimum and maximum rim width specs can be found on your favorite tire manufacturer websites. Just for reference, I checked on Kumhos website. They listed their 225/45 SPT tire to have a minimum rim width of 7.0" and a maximum of 8.5". Thus, it is probably not a good idea to try and mount 225s.

 

[jtmcinder]

Pro3racer -

Do it once. Do it right. Buy new wheels that are as wide as allowed by the class you run in. Buy tires that will be happy on these rims. Put some Futuras on the stock wheels for the rest of the time.

Happy, grippy tires are the most important mod for autocrossing. No other mod comes close.

- Jtoby

 

[Slow99x]

I didn't know that about rental companies. Could the final drive in the 97-99 AWD effect this? I know it's different than the 95-96. Is it possible that the gear itself is the same but effected by the gearing of the later model? I'm not trying to argue but I'm just trying to figure out why my speedo is exactly right and my friends was wrong.