taller than stock tires

stangguy

stangguy

Joined
Jul 14, 2020
Messages
527
Ok, so I have a chance to get a really good deal on 4 almost new tires for my 1998 mustang V/6. The only thing is that the size is about 1.5 inches taller than the stock size. I am wondering if that will be a problem gearing it up that much. I know the speedometer will be reading slow, but that doesn't concern me. Just wondering if my low power engine and automatic trans is up to it?? Sometimes I drive on hilly roads, not mountains but some pretty good hills.
 
I got a really good deal (free) set of new tires put on a rarely used car that were about and inch smaller than stock. Every time I drive the thing the speedometer being off annoys the heck out of me and the car also looks noticeably lower than it should. If I had to do it over again I'd have paid for a set of tires the correct size.
 
mrsilv04 said:
It will have an effect on your gearing, that's for sure. There are online calculators out there, if you plug in the details, that it will tell you what your "new" rear end gearing will be with the different sized tires.
Click to expand...
Yes I know that I can figure the new gearing, but wondering if that gearing will be a problem, or not.
 
stangguy said:
Yes I know that I can figure the new gearing, but wondering if that gearing will be a problem, or not.
Click to expand...
Without any details... it's only a guess. You're asking for an answer, when only providing part of the information needed to get to that answer. What is your gearing now, and what will it change to?
 
Look up the torque curve. If it's relatively low it would probably be ok as long as you don't have a heavy foot. You might get some premature shifts though. That's 3/4" more sideway. You'll also want to make sure they don't scrub on the front anywhere like the top of the strut, etc.
 
stangguy said:
Yes I know that I can figure the new gearing, but wondering if that gearing will be a problem, or not.
Click to expand...
What rpm to you run at 60mph now? If its above 2000 rpm I bet your fine. I went up almost 1" in diameter of the Focus for better ride, less rpm, more fuel efficiency, and its worked out well, as the engine turns nearly 2500 rpm at 60. I tried the same thing with an 06 CRV but it ran out of torque in top gear often with oversized tires, and with all the downshifting it used more gas.
 
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IndyIan said:
What rpm to you run at 60mph now? If its above 2000 rpm I bet your fine. I went up almost 1" in diameter of the Focus for better ride, less rpm, more fuel efficiency, and its worked out well, as the engine turns nearly 2500 rpm at 60. I tried the same thing with an 06 CRV but it ran out of torque in top gear often with oversized tires, and with all the downshifting it used more gas.
Click to expand...
I am only running at about 1800 at 60 mph. So, I guess I better stay with stock size wheels. and it downshifts on much of an incline now.
 
It will be a dog accelerating. I wouldn't, as it'll also effect handling, but how much money are you talking about saving? AFAIK stock tires would've been 205/65/15 which isn't an expensive size. If not picky you can get new for under $75 each. If it were the 4.6L V8 I'd think performance tires are more important but with the old 3.8L V6, I'd stick with similar size if not a little wider for your hilly (suggesting also twisty?) roads, max being around 225 for the stock 7" rim (then consider dropping sidewall to 60) or 215 a nice compromise, depending on what you find.

OR, are the numbers above off, considering I saw your topic last year about larger rims?
https://bobistheoilguy.com/forums/t...ustang-wheels-on-my-1998-base-mustang.335426/
 
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Assuming you're moving from 205/65/15 to 215/65/15, there isn't going to be much of a difference. At 70mph on your speedo, you'll actually be going 71.5mph

If you're moving to 205/70/15, at 70mph on your speedo, you'll be going 72.2 mph. I am running this size on my 1999 v6 and there is pretty much no difference in acceleration or fitment.
 
What about clearance in the wheel well? Particularly on front tires. Might they rub on sharp turns? What about winter, when the wheel wells get packed with snow?
 
Online you can find specific tires revs per mile. look up stock tires, Look up new tires and divide the numbers to find the % difference. Apply that % to speed or rpm to find how much change. I put oversize tires on everything and usually the difference amounts to a few hundred rpm or a couple mph. wont affect the car much at all. larger diameter should ride better.
 
Before one has gearing problem with tires they must fit inside wheel wells.
Do they fit without rubbing?

Krzys
 
First, I am not aware of anyone that publishes a fitment guide that will tell you what tires will fit under the fenders without rubbing.

But 1 1/2" sounds like those would rub - very bad.
 
Here is a pretty good site that shows the differences between your OEM stock size vs. any other tire size you enter. Scroll down and it "tells" you what pros/cons performance traits you might encounter with a different size.

I was recently looking at alternative tire sizes for my Patriot's 205/70R16's with limited brands/models available.

https://www.wheel-size.com/calc/?wh...65-16X7ET44&fcl=50mm&scl=50mm&wcl=30mm&sr=0mm
 
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