Tire/Brake Questions
 

Hey all, couple questions.

First, Im wondering what the widest tire i can fit on my 86 GX is. I just got a set of 5-Zigen Copse rims, 17x7.5 with a +42 offset. I know its not ideal, but they were the right price, and they look amazing. I would like to get something like 245/45(or 50)/17's, but I dont know if that will rub, and tire places around here dont want to fit a tire, just to see if it will rub or not.


Second, I just ordered some rotors, and they should be here soon. Would it be possible for me to change the rotors and put on new brakepads, having never done it before? I have all the tools for it (i think?).


Thanks,

Dan

Hey Brass ..how ya Doin?..For the Tire and wheels..best off is to Take a Look at "the official tire and wheel fitment Thread"..here on the Rx7club forum ..it will basically answer anything you can throw at it..NOW..for the Rotors and Pads..I can only think of the 2 SCREWS that hold the rotor to the hub being a "B%$#H" to get off..then Once you get those off .you should smack the shit out of the face of the Rotor..To loosen up the corrosion that has Pretty well "welded" the rotor to the hub by now..If and When you get them off <>ANTISIEZE will be your friend<>..For future Rotor removal..and don't forget to Lube the brake sliders and check the caliper piston seals for cracks etc(antisieze the wheel studs a touch too) ..Good Luck to ya..(you may want to Read IMLOGAN'S thread too..New project,New Owner..It explains what you "may encounter)..sincerely Misterstyx69

thanks a lot, I will look into it.

Well I just test fit a rim on the front, and the back. In the front, it JUST fits without rubbing. In the back though, it seems that i have a lot of room on either side. I can fit at least 3 fingers all the way around the inside, and on the outside there still looks to be lots of room before it would hit the fender.

So....good new then??

Well I just test fit a rim on the front, and the back. In the front, it JUST fits without rubbing. In the back though, it seems that i have a lot of room on either side. I can fit at least 3 fingers all the way around the inside, and on the outside there still looks to be lots of room before it would hit the fender.

So....good news then??

The correct tire sizes to get the closest to correct diameter for the FC are 235/40/17, and 245/40/17, neither of which are reccomended for a 7.5" wide wheel. I looked up some tire specs and for the ones I looked at the reccomended range had an 8" wide wheel as the smallest they advise using. You can probably fit them on the wheel, but it's not ideal.

If you run taller tires you'll get slower acceleration and the speedometer will read incorrectly.

Hmm....I just looked up some specs on some tires i am interested in, and yes, it does say that a 40 series is recommended with an 8" wide rim. However, it also says that a 235/45, or 245/45 will work with a 7.5" rim. Right now my speedometer doesnt work anyway, so not a big loss there. Would it even be a noticeable acceleration difference between the 40 and 45 series??

Not a huge difference, but it's there.

Another problem that can arise from running larger diameter tires is rubbing (usually against the fender liners), as the tire is further into the wheel well under all conditions, so in some cases a shorter tire may not rub, but a taller one will.

there was a thread similar to this just a week or two ago....anyways, you are going to need a spacer up front, i will tell you that right now. most any size tire on a 7.5 inch width with a +42 offset is going to hit the suspension. you are going to need a big spacer for a 245.

try to keep within the stock overall diamater. what you don't want to do is go OVER the stock diameter. this will hurt your acceleration a bit, and you are asking the suspension to work with a diameter it wasn't designed for.

the biggest i would recommend on the 7.5 is a 235/45/17. you are going to need a decent sized spacer up front though, and in the rear you might also need a spacer...
the rear has more clearance than the front, but if you need a spacer in the rear you will most likely need longer studs since the stock are too short.

Thanks, I think I am going to go with a 235/45/17 GoodYear FIERCE tire, its brand new and apparently really good.

So I went to foundtain tire yesterday, and left my rims there. They said that they would be ready, with the tires on them today, so that we could just throw them right on the car. For the past 3 days i have been dreaming of 235's on the back, and how awesome it will look with my new rims.

So I go there today, hoping that they will just throw them on, and im on my way. But wait? whats this?? The head manager guy tells me that THEY WONT FIT ON THE RIM. Fair enough, its not a very wide rim, so lets try a smaller size. 225? 215? no and no. He claims that the BIGGEST tire that can fit on a 7.5 inch rim is a 205, and thats pushing it. Claims that sidewall has nothing to do with it either, so even a 225/50 wont fit.

WHAT THE HELL?!

So I'm very upset right now, because i will probably have to sell my rims (that i JUST got) because there is no way in hell im driving around with 205's on the front and back.

You should tell him that he's full of shit. I looked up some Goodyears in that size (couldn't' find the specs for the Fierce) and they say that it's fine on a 7.5" wide wheel. So if Goodyear thinks it's ok, then why won't he do it? You can fit up to a 225/45/17 on a 7" wide wheel, so why he thinks that a 205 is as wide as you can go on a 7.5" I don't know. Sidewall does have some effect on the tire and rim width match. Taller sidewalls mean that you can run wider tires on a narrower rim (within limits).

If they won't put the tires on the rims then you can either buy the tires and take them some place else to get them mounted, or just get tires from somewhere else. If I were you I'd go somewhere else with my business unless you've already paid a deposit or paid for the tires.

I definetely wouldn't go back there, as they don't have a clue what they're talking about.

You do not need to sell your rims because of tire size!!!!

He claims that putting a larger size on, means that the side wall has to be squeezed. Then, the tire will "crown", meaning that it will bulge in the centre. This will apparently cause the car to always be rolling back and forth, and not allow the car to drive properly.

I want these rims, but I also dont want any problems with my car.

go find another tire place.

if you want to know the recommended wheel width, go to the tire manufacturer's site. a 235 will fit on a 7.5 for almost any make of tire.

right now i am running 225/50 on a 7 inch wide wheel, and that is a normal size, fits fine.

thats exactly what i had found also. Online, and in catalogues, they all say that a 235 will fit on a 7.5 inch rim.

no one here has problems with this "crown" the guy is talking about??

Back in the stone age, with bias ply tires, if you put a too wide tire on a too narrow rim, the sidewalls would be pulled in and the tread wouldn't be flat, but would be curved (crowned). That isn't true of radials (unless you're trying a really radical mismatch of tire and rim width). As others have said, a 225 should be fine on a 7 inch rim. This guy doesn't know much about tires.

I'm often amazed at how little some tire shops know about tires.

Alright, thanks a lot. I am going to go to a different place, and hopefully get someone to do something for me.

Well I went to a different Fountain Tire, and the guy literally said "He doesnt know what hes talking about." Called up that store, got the tires sent over to his location, and put them on for me today.

And it looks effing amazing!