Berlyn0963

iTrader: (4)

can somobody tell me Every possible tire size that will fit on a Rally Sport 15x7 inch rim?
i'd greatly appreciate it cuz i dunno what tires to order
thanx

MDv6man

Anything that ends with "R-15" will fit on the rim. I think 275's are the largest tire that will fit on the car.

TomP

Yeah, I've got P275's on the back... before that, I had very big P255/70r15's back there, and had to massage (haha) the inner rear wheelwell with a sledgehammer. They fit with an inch clearance. When I went to the P275/60r15's, they had a bit more clearance- the tire is shorter than the P255/70's I had.

Looks like I'll be going to a P255/60r15 soon, though. I think I'm going to lose the huge tire and air shock look, and just go with a big tire. (Fronts are P225/60r15's... a bit wider than my P215/65r15's, but same height).

Oh, er, yeah, say you like your tires now, but you want them a bit wider. Just do some conversions... grab tire sizes, and do the following easy calculations. I'll use my original front tire, P215/65r15, as the example.

P215/65r15
P=passenger
215= section width
65=aspect ratio, "percentage"
15=rim size

215 divided by 25 = converts to inches = 8.6 = tread width
8.6 times 0.65 = sidewall height = 5.59 inches

For tire height, remember, you have two sidewalls (top and bottom), and a rim in the middle. So multiply the sidewall height by two, and add the rim size:
5.59 + 5.59 + 15 = 26.18 inch tire height

Now, these are all approximates, two tires, same size stamping, by different makers, can be slightly different sizes due to different manufacturing methods. But, they're close enough. So I wanted a front tire that was a bit wider, but the same size. There's more complicated ways of doing this, but I just took the next wider tire, and ran some calcluations on it, and it worked:

P225/60r15: 225/25 = 9.0 inches wide. 9 times 0.60 = 5.4 sidewall. Tire height = 25.8 inches.

So I wound up with a tire that was a bit wider, and a bit shorter. This is also good because you can use your existing tire as a beginning point. Say you want to run a P235/60 on the front, but you're not sure it'll fit. Run the calculations, you get a tire that's 9.4 inches wide and 26.28 inches tall. Your current tire is a P215/65r15, 8.6 inches wide, 26.18 inches tall. The height is negligable, maybe 1/8 to 1/4 inch difference. But, the tire is now almost an inch wider! So measure a half inch "extra" from the inside and outside of each tire; see if it'll fit. Got what I mean?

Remember too- a tire too drastic in height change will affect your speedometer. Taller tire = speedometer reads "slow" (you're doing 68 but your speedo says 55), and that's asking for a speeding ticket! Shorter tire = speedometer reads fast (you're doing 50 but your speedo says 60). So try to stick with tires that are close to the same size.

Also, if you put a very wide tire on a thin rim, the sidewall won't look flat, it'll look "bubbly". My P255/70r15's fit on my original 15x7 rims, but the sidewalls looked very round... when I changed the rear rims to 15x8, the sidewalls flattened out.

A wider tire will hydroplane easier, get less traction on snow, and your car will like to "wander" on the highway. Know those grooves caused by small car tires? Well your wide tires will want to be half-in and half-out, and on an old highway, you might be fighting the steering wheel every now and then.

One last thing; remember that our front tires like to rub the inner wheel well on sharp turns... keep that in mind when going to a wider tire. A good idea might be to stick with "optional" tire sizes for f-bodies... for instance, my p225/60r15's on the car now were an optional tire size. I think the P235/60r15's were, too... but don't quote me.


When in doubt, check with your tire shop...

TomP

You can go to summitracing.com , click on the online catalog, then wheels and tires, then tires, then choose BFGoodrich radial t/a's. Click on a tire (make sure for a 15" rim), and then click on technical, they have recommended rim sizes.

V6camaroman

watch out for those 255-60-15 tires tomp. ive got those on my bird and i had to get air shocks because the tires would rub going over bumps

Berlyn0963

iTrader: (4)

http://www.tirerack.com/tires/tires....tnum=25HR5E711

i hope that link above works but if U dont see it go to the Tirerack.com
225/50/HR15 51 bucks a piece Kuhmo Ecsta 711 they arent out on the market yet cuz i called today and said that the manufacturer hasnt gotten off thier lazy asses and made them yet so i gotta wait until October
the tire appearently has excellent dry summer capabilities but wont go anywhere in rain or snow. so i was told.


but its cheap and looks good and i could care less about rain and snow but im concerned about the front tire clearance when turning
if i wanna get a different size so it is not as wide as the rear but is the same height or profile what size would it be?

TomP

Oh, really? Darn, I want to get rid of my air shocks. Where did the P255's rub? My P275's will cut the outer lip of the quarter panel... in fact, I had my shocks aired down one winter (for traction), and backed down a driveway quickly- the car bottomed out, I ripped a chunk out of the tread, AND bent the damn quarter panel lip.

V6camaroman

when i had my 255-60-15 tires on before the air shocks when i would go over a bump the tire would rub on the outer quarter panel lip. i dont know if yours will or not. what is the back spacing on your rims? my 255's are on cragar key stone classics 15x8 reverse offset rims. so they stick out quite a bit.

Berlyn0963

iTrader: (4)

as i said b4 i GOT STOCK RALLY SPORT RIMS 1991 GM MAUFACTURED THE INVERTED SILVER 5 STAR 15x7

ummm is anyone gonna answer my questions?

V6camaroman

i would say, just get a set of 225-60-15 for all 4 corners. but if you want the biggie small look get a set of 205-65-15 tires for the front and 245 or 255-60-15 tires for the rear. my friend had a 86 z28 and he had 215-70-15 tires on all 4 corners. that looked ok

Gumby

Im runnin Dunlop SP5000 225/60ZR15 on stock size rims with out any problems. Only a slight rub in reverse when i turn really sharp.

I do have coil over shock and lift studs but only to make the car level or look level. So there is the same ammount of gap from top of fender to top of the tire all around.

TomP

Berlyn, like I said before, you can always work through the measurements of your current tire and the "new" Kumhos, and use the measurements to see how the new tire compares to your old one.

v6camaroman, not sure of the backspacing; I'm pretty sure it's a stock kind of number. All I did was go to pep boys and tell the guy that I needed 4 rims for an '86 Firebird, 2 fronts are 15x7, 2 rears are 15x8. He called american racing and placed the order. I still have the boxes inthe basement, I'll see if they have the backspacing marked on 'em. I think they did...

my91rs

Here is your answer.........Before i got rid of my factory 5 star RS rims. I had 255/60-15's on the rear and 235/60-15's up front. And drove from Ft Myers Florida too Houston Texas w/ out not rubbing or problems. And no air shocks. In fact, I m thinking about going back to the 255's in the rear again w/ my Centerlines I have now. As far as now . I have 245/60-15's on the back and 225/60-15's in the front now. I just like to look in the rear of my car and see that fender well space filled. And not look like a donut spares are on my rear.

TomP

LOL... and then, after big tires, putting that donut spare on looks even WORSE! (remember using a donut spare on a posi can burn a posi out, so be careful)

pontiacguy1

I know that a lot of you guys have done different, but for the best mileage out of a tire, I believe that you probably shouldn't go wider than 245 on a factory 7 inch rim. I used 255-60-15 tires on the rear of my truck, and the center wore out faster than the sides. They were not over inflated, either. I usually ran them at 28 PSI, but because the tire was wide and the rim was narrow, it caused the center to bubble out. Now, I am not claiming that the tires were ruined way quick or anything, but they could have gone another 6 or 7K miles if the wear would have been even. I had 235-60-R15 tires on the front running at 35 PSI, and this didn't happen. I would go with 235-60-R15 all the way around, and then rotate the tires every 5K miles. That will give you a larger footprint then factory,and will also give you the longest wear rate. Your speedometer will read slow by about 3 MPH or so, though. Just my .02 worth on this topic.

Oh, I was using factory 15"x7" trans am wheels, which are the same dimension as the Camaro ones.

TomP

I agree; the P255/70's I had on the old 15x7 rim had really bubbly sidewalls. Moving to the 15x8 rim helped a bit, but you could still see a bubble. I don't think the P275's would've even fit on a 7 inch rim! V6CamaroMan, how's the sidewalls with your P255's and the 8 inch rim?

Gumby

"I usually ran them at 28 PSI, but because the tire was wide and the rim was narrow, it caused the center to bubble out. Now, I am not claiming that the tires were ruined way quick or anything, but they could have gone another 6 or 7K miles if the wear would have been even. I had 235-60-R15 tires on the front running at 35 PSI,"

buy a better brand of tires, hehehehe

**** even if it says 35 I run about 40. My dunlops go up to 52 psi. I run 50 in the rear and 40-45 in the front. and it says that the 52 psi max is only for usa and canada, meaning you could run more.

We are drving sports cars here guys and the only thing between you and the road is the tire. get some good z rated tires [149+ mph] with a proper psi range if you like to hang it all out.
www.discounttiredirect.com has the best prices. my dunlops cost 150+ each in the store. I only paid 65 each online but the price has gone up since then. but free shipping now. so it about even.

rain, snow, shine, they stick.
http://www.discounttiredirect.com/dt...odeIndex=28604

pontiacguy1

The tire was just too wide to work real well on those rims. I just don't want anyone else doing that, then having to spend more money sooner buying new tires. Maybe you should have said 'get some better rims' which would've made my tires wear correctly.

My comments above were to help size some tires, and save the guy some money in the long run. Most of us can't afford to get new tires every 15 months or so, and even if we could, that money could be put into other things like Nitrous, ignition, suspension, paint, or maybe that turbo project everyone always talks about! Just puttin' in my opinion.

Gumby

im using stock size rims with out any problems.

I originaly had the dunlops on the stock rims but they had seen 15+ years of abuse so I found the cheapest rims I could get that were new and straight. I would have bought plain stock rims again. ended up being the cheapest ones I could find were chrome but they are the same size as the stock rims. but new and stright.

you would be suprised how well a car feels at high speeds after getting new rims.

Ryan_Alswede

which give you better ride, gas or oil based shocks??

which last longer??

Gumby

which give you better ride, gas or oil based shocks?? oil

which last longer?? gas


oil shock with a set of coil over springs are the best ride i have ever felt. but no one carrys the oil shocks anymore. well the o-cheap-o local auto parts store.

oil will blow out if you fly over tracks or baha in the rough city treets. but it rides so well. that is for 7-9 buck a shock.