Tire Size & Air Pressure for VW Based Kit

[Ed Summers]

Hi folks, I have asked several questions about my MGTD and you have always given me great advice. The tires I have on the Chevette based car appear to be over ten years old maybe as old as 19 years. The ride is not very smooth and there is an inconsistent front in shake around 50 mph. I feel I need to replace the tires. Is there any reccommended brand/size etc?

 

Thanks as always

 

Ed

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[Mark Hendrickson]

Hi Ed,

If you look at the picture of the “Pink MG” in the gallery, you’ll see the new 14″ x 6″ rims (by US Wheel) and the P185/70R-14 Sumitomo tires on the car.

Due to the lighter weight, you don’t need a lot of air pressure. I started with 20 lbs all around and adusted the air pressure to detect the changes. You’ll find a pressure you can live with that keeps the tire wearing properly and doesn’t give a brick like ride.

When Bill Collins VW based “Angelica” was my first “Pink MG”, I ended up with 14 lbs in the fronts and 18 lbs in the rears to get the desired handling. This was after removing front leaves and reducing the diamter of the rear torsion bars too. The car had stock VW sized P165/80R-15 tires.

I have access to a tire machine and Snap-On dynamic balancer at the local Navy Base’s Auto Craft Shop. I buy tires from http://www.tirerack.com and mount and balance them myself. I have also bought from http://www.discounttiredirect.com with equally good results.

Whatever you buy, be sure they clear and are not too wide for your rims. I think the OEM Chevette rims are 5.5″ wide and 13″ in diameter. You may want to invest in a 14″ rim, like I did. If not, a P16580R-13 or P175R75x13 might be a good choice.

[Bill Hursh]

Hi Ed,

I checked the size of my tires on my chevy based TD. They are P195 75/R14. I run the tire pressure at mfg recomdations. I also had a shake in my car upon the completed assembly. I found 2 things that helped. The tires on the car during assembly, though new, had flat spots from setting for extended periods. The other thing I found, the front shocks, even though they were new, were leaking oil. I was able to match them to a new set of gas charged shocks and she drives like a dream. I hope this helps. Good luck.

Bill Hursh NY

[thomas swartzwelder]

I have read in several places about the tire pressure differential to improve handling and i assume it is necessary due to the weight difference in the VW powered cars. My question is: Is there a ratio front to rear pressure that occurs frequently? By this I mean that I understand that each car will differ but is there a logical or experiential starting point or is it trial and error all the way? Thanks for all your help so far.

[Mark Hendrickson]

My VW based TD had P165/80R-15 tires on OEM VW “Baja Bug” rims. Same as the tires that came on the VW.

Experimenting with tire pressures, I used ride, cornering and the tread pattern in sand to determine what I eventually ended up with.

Keep in mind, my OEM VW suspension was correctly modified for spring rate front and rear.

I started with 24 lbs per tire rear/22 front…ride too harsh, center tread left deeper pattern in sand, cornering was OK.

I went to  22/18 and things got better in the ride department, more of the tread was meeting the road and the cornering got even better.

I went to 20/16 and the front tires left a great pattern in the sand, rode better, the rear tires left a deeper tread pattern almost even across, but the rear tires started a slight squeal under hard cornering.

I went to 20/14 and it seemed to be great all around. The ride and cornering were good, no more rear tire squeal and an evenly deep tread pattern in the sand.

About a month later, I got to scale the car at a buddy’s race shop. A pound of air in the tires made a 16 pound change in the wheel that got the extra air. I went back to my orgininal 20 rear/14 front and it was the best we could get the car for balance.

[Paul Mossberg]

FYI to Ed…if you go looking for this thread, I changed the subejct to Tire Size and Air Pressure. I didn’t know I could do that!

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Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster

If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

[thomas swartzwelder]

thanks again for the valuable information. It gives me a good place to start. Hope to have my TD inspected in the next day or so. The procedure in NC is quite convoluted for a “reconstructed car from out of state” Wish me luck.  Thanks again  tom

[Paul Mossberg]

OK. Here ya go…

Good luck Tom.

Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster

If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

[Bailey]

tomscs wrote:

thanks again for the valuable information. It gives me a good place to start. Hope to have my TD inspected in the next day or so. The procedure in NC is quite convoluted for a “reconstructed car from out of state” Wish me luck.  Thanks again  tom

Good luck, you may need it!  I had so much trouble that I got a SC title.  Luckly I live in Charlotte and have a daughter just acrosss the line in SC. 

Let me know how you come out. Are you close the the Charlotte area.

[thomas swartzwelder]

Bailey, I live in Rocky Mount. I have been given guidance on the registration from a gentleman here who restores classic cars. Sorry to hear of your difficulty. I will post my results.

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